this is bbc world news, i'm reged ahmad. our top stories: hours before voting was due to begin, nigeria's presidential election is postponed for a week. donald trump invokes national emergency powers to fund the border wall with mexico. his opponents are furious. we are going to confront the national security crisis on our southern border, and we are going to do it one way or the other, we have to do it. the family of the pregnant teenager who joined the islamic state group pleads with the british authorities to help bring her home. and, junk in space: engineers test a new satellite harpoon—system for collecting floating trash. hello and welcome to bbc news.

we start in nigeria where the electoral commission has postponed the presidential election by a week, just a few hours before voting was due to begin. the commission chairman yakubu mahmood said that it was not logistically feasible to go ahead. this is what he had to say a little earlier. the commission came to the conclusion that proceeding with the election as scheduled is no longerfeasible. consequently, the commission has decided to reschedule the presidential and national assembly elections to saturday 23 february 2019. our correspondent mayeni jones is in yola, north—east nigeria. i asked her what the reaction has been to the postponement. yes, the ruling progressive congress was the first party to release a statement, they said

they condemned the delay. they called for supporters to be patient, urging them to turn up on the 23rd when the vote has been rescheduled, but they also blamed the opposition, the people's democratic party, for the delay. saying they hoped the electoral commission was not colluding with them. the leader of the opposition shortly atiku abuba kar later released a statement expressing disappointment and the delay and the his supporters to remain calm but blaming the ruling party that they feared losing the election. any further insight about why the decision was made by the commission?

no, yakub mahmood said he would provide more details later on saturday. there had been a few fires in a few polling stations in central nigeria and the south—east. as of yesterday, friday, we were still getting reports that many polling stations still had not received ballot papers and essential voting materials. there have been a few logistical challenges in this election. 84 million registered voters, offices in part of the country that are very remote and these may have been some of the factors contributing to the delay. we have heard for a call for calm, but what kind of reaction can we anticipate from voters waking up hearing the news, when they were expecting to go to the polls? i suspect there will be a lot of disappointment. many people travelled a long distance to vote. many volunteers have been deployed all around the country to man polling stations and have been

sleeping in uncomfortable conditions and they will be disappointed at having to do that again, and then there are observers and journalists all over the country who will not be able to cover the elections. people will be asking a lot of questions. the commission had four years to prepare for these elections. why it were they not prepared? in the past, elections had led to violence so people will be looking closely to see how people react, but it is encouraging that both main parties have urged supporters to remain calm. you have spoken of events in the past. it is such a last minute decision, how unusual is that in the contexts of elections in nigeria? it's not particularly unusual.

in 2015, the polls were postponed due to insecurity in the north—east. then the voters were given six days notice. in 2011, the national assembly elections were postponed on the day so it is not particularly unusual. but the 2011 elections were marred by a lot of violence after the results were announced, about 800 people were killed in clashes in the north of the country. elections here are fraught with lots of violence and tension. many people potentially worry they have the potential to destabilise the wider region. after weeks of speculation, president trump has defied his critics, and many in his own party, by declaring a national emergency. it means he can now bypass congress, to get the billions of dollars he says he needs to build a border wall with mexico. those funds will come from other government departments. but democrats have launched

an investigation, saying the move is unconstitutional — and they'll fight him all the way to the supreme court. 0ur north america editor, jon sopel has more from washington. ladies and gentlemen, the president of the united states. donald trump had an unpalatable choice. having not got a deal with congress, he was either going to have to admit failure on funding his wall with mexico, his signature campaign pledge, or he was going to have to go nuclear. he chose nuclear. this was now a national emergency on the southern border. we're going to be signing, today, and registering, national emergency. and — it's a great thing to do, because we have an invasion of drugs, invasion of gangs, invasion people, and it's unacceptable. watched by relatives who have had family members killed by illegal immigrants, the president rode roughshod over the powers of lawmakers to set budgets and to set up a confrontation with congress that he fully recognises is likely

to end up in the courts. we will have a national emergency and we will then be sued and they will sue us in the ninth circuit, even though it shouldn't be there. and we will possibly get a bad ruling and then we will get another bad ruling, and then we ‘ll end up in the supreme court. and all the time the courts are deliberating it means there will be no substantial building work taking place. less building a wall than hitting one. but here's the problem. there's a lot of of fencing and structures, but there are places where it just ends, so people like his mother and child from guatemala can just walk round it. "my little girl is hungry," she says, "and i don't have any money." in recent years, the number of illegal immigrants trying to enter the us has been in decline. and most of the drugs that enter the country from mexico come from legal crossing points — like this one. but a lot of border patrol officers who backed the president's call for a wall make this point

about the problem subsiding. i would say it's nothing like it was. i would say that it's changed. but that is the equivalent of saying your house is only getting robbed one day out of the week now, instead of all seven, then you're done. we're not done. back in washington, the democrats are considering their next move. it's hard to believe they won't challenge this. president trump couldn't convince mexico, he couldn't convince the american people, he couldn't their elected representatives to pay for his ineffective and expensive wall. make no mistake, congress will defend our constitutional authorities in every way that we can. donald trump's signature is now on this declaration. there are many on both sides of the divide who question how much of a national emergency this really is. and it won't be lost on them that on day one of the emergency the president flew off to his golf course in florida, not the border with mexico.

let's get some of the day's other news. the turkish president, recep tayyip erdogan, says his country is determined to take the investigation into the killing of the saudi journalist jamal khashoggi to an international court. mr erdogan said turkey had not so far disclosed all the documents and information it had concerning the killing, but would deliver them to investigators. five people have been killed in a shooting at a warehouse near chicago. police said the gunman was shot dead by their officers. it happened in an industrial area on the outskirts of aurora. at least five police officers are amongst the injured. relatives of a teenager from london who went to join so—called islamic state have asked the british government to help them bring her home. the family of shamima begum, who was 15 years old when she left the uk, said they understood she would be investigated and they welcomed that. there's also a new warning

from the head of britain's intelligence agency, m16, that thejihadists still pose a threat. daniel sandford has more. inside the al—hol camp in northern syria, the women and children fleeing the fighting in one of the last strongholds of the islamic state group. this is where the former bethnal green schoolgirl shamima begum is. her family had lost all hope of seeing her again. and tonight, in a statement, they asked the british government to help them to return her, along with her unborn baby. they said they would welcome the police investigating her, something that is inevitable if she returns. we have to be clear that people who leave this country to support that regime are people who,

if they do return, have to answer for their actions. some 850 people left the uk to join is and around half have already come back. today alex younger, the head of the secret intelligence service, mi6, warned that at least some returnees will pose a risk. the home secretary said this morning that he would prevent those involved in terrorist organisations returning to britain. but what does that mean for shamima begum, who left the uk as a schoolgirl? could she have her citizenship taken away? if she doesn't have another nationality, as i believe to be the case, then it is morally unacceptable to refuse her entry — as well as legally unacceptable. because otherwise she would be stateless. and no person in the world can be stateless under the law. her family said they were shocked

to hear her say she didn't regret going to is. they explain it by suggesting that she was groomed at the age of 15 and might have been wary of what she was saying in a camp surrounded by is sympathisers. and rashad ali, who is an expert in de—radicalisation, says is supporters can be turned round. we know in the uk we have worked over the last ten years with fairly hard—line violent extremists who have renounced their ideology, have remorse for their actions, and have taken part, actually, in helping others move away from extremist tendencies and violent ideologies. the kurdish red crescent says there are around 1000 new arrivals at al—hol just this morning. decisions will have to be made soon about what to do with the british is supporters among them. later saturday the funeral

for the footballer, emiliano sala, will be held in his home town in argentina. the 28—year—old was killed in a plane crash, while travelling to his new club, cardiff city. kim gittleson has more. a hometown hero returned too soon. for the residents of this small argentinian town, this was not the way they wanted to welcome back one of their most successful sons. translation: without a doubt, we would never have imagined everything that we are seeing now. there are 3000 of us and we remain shocked and overcome by the situation but still trying to give emiliano sala the farewell that he deserves. emiliano sala grew up playing football here in progreso until the age 01:14, when he left the pursuit bigger opportunities. —— to pursue bigger opportunities.

but recognition seemed to come belatedly to the 28 year—old, when he was bought by cardiff city from nantes, for a club record of $19 million on the 19th of january. but then, just two days later, the plane carrying him and pilot david ibbotson from france to his new home crashed into the english channel. after a two—week search, mr sala's body was found in the wreckage. mr ibbotson‘s remains missing. now the residents of progreso are preparing to say theirfinal goodbye, while promising that emiliano sala will stay eternally in their hearts. stay with us on bbc news, still to come: making their voices heard — children from across britain skip school to protest about climate change. nine years and 15,000 deaths after going into afghanistan, the last soviet troops were finally coming home. the withdrawal completed in good order, but the army defeated in the task it had been sent to perform. malcolm has been murdered.

it has a terrible effect on the morale of the people, i'm terrified of the repercussions in the streets. one wonders who is next. as the airlift got under way, there was no letup in the eruption itself. lava streams from a vent low in the crater flowed down to the sea on the east of the island, away from the town for the time being, but it could start flowing again at any time. the russians heralded their new generation space station with a spectacular night launch. they've called it mir, the russian for peace. this is bbc news, the latest headlines: hours before voting was due to begin

nigeria's electoral commission blames logistical reasons for postponing the presidential election by a week. donald trump invokes national emergency powers to fund the border wall with mexico. the democrats accuse him of "an abuse of power." schoolchildren across the uk, have been taking part in a day of protests, calling for action on climate change. 0rganisers say pupils walked out of schools in more than 60 towns and cities, to highlight what they see as a lack of action by the government. frankie mccamley reports. we are angry that the government's not doing anything, but we also see it as important to fight for ourfutures. to all the politicians, listen to what we have to say. you failed at saving your own future, so now can you try and save ours? there's no time to rest. we have to do something to save the planet. chanting: this is what democracy looks like!

different voices, one clear message. today was a day led by the children, for the children and their future. thousands campaigned in dozens of protests across the country. they say you don't have a voice! a call for action in sheffield... what do we want? climate action! chanting in ullapool. .. marching in brighton... a real sense of urgency in cardiff and, in manchester, there was music. # born to love in everyone... before nine—year—old lilia had her say. i'm worried about climate change because of the animals. would you like it if your home was disappearing in front of your eyes? this is clearly the first time many of these pupils have ever walked out of school and, just by looking at the age of some of these, the first time they've ever been on a protest, but their message is clear. they want to protect the future of the planet and safeguard their future.

the action is part of a much wider global movement, inspired by 16—year—old greta thunberg from sweden. she's been striking from school every friday, calling on her government to lower its carbon footprint. you are not mature enough to tell it like it is. even that burden you leave to us children. her persistence later sparked protests across the world — from australia to belgium and ireland earlier this week. the government has said today's protests are a waste of lesson time and increasing teachers‘ workload, but the threat of school disciplinary action pales in significance to the danger these youngsters think the planet is under from climate change. frankie mccamley, bbc news, manchester. engineers say they've successfully found a new way to tackle the build—up of space debris. a team from the uk have used a harpoon—capture system on board a satellite to collect orbitaljunk. 0ur science correspondent,

rebecca morelle reports. this is the moment a harpoon was fired in space. striking a target almost dead centre, it was filmed 250 miles above the earth. it's the latest experiment from the remove debris spacecraft. led by surrey university, it's a mission that is testing out the technologies that could clean up space junk. it was absolutely a success and the goal of the experiment was to hit the target and that's what we did. it's important because there's so much debris up in space, from spacecraft that are no longer operational to bits of rocket body, and we need to start clearing some of this debris out of the way to make way for new spacecraft. space is becoming increasingly cluttered. it is estimated there are now nearly 8,000 tons of debris, with 800,000 pieces the size of a marble or bigger, and each piece has the potential to do some serious damage. in 2016, this crack in the window of the international space station

was thought to have been caused when a tiny fleck of paint hit it. bigger objects could do even more harm. scientists are particularly worried about a european satellite the size of a double—decker bus that stopped working in 2012. it's now threatening other satellites in its path and needs to be removed from its orbit. last year, the remove debris spacecraft also tested a net, proving it could catch a passing satellite. it's the first mission to try and address this problem. and it's also used its onboard cameras to track a tumbling target. essential for hunting down any rogue space litter. its final test will be in the coming weeks. it's set to burn up as it returns to earth, preventing it from becoming a piece of space junk itself. the hope is now that future missions can be scaled up so the celestial

deep clean can begin. a group of american researchers has announced a plan to develop gene—edited animals to help poorfarmers in africa. they'll work alongside scientists in scotland, who are looking at ways to develop animals that are more resilient, productive and resistant to diseases. here's our science correspondent, pallab ghosh. just a few hours old. these are among the world's first gene edited pigs. they are in into a lethal lung disease. the animals have been created from fertilised eggs surgically removed from a pig. around 20 per animal are flushed out. the plan is to develop farm animals for subsistence farmers in africa, which are resistant to a range of diseases. engineering

disease resistance in two animals will have a huge impact in a farming community in africa where people have much smaller pot elation sizes and the death of one of two animals is disproportionately catastrophic that community. —— population sizes. so how does it work? the virus latches onto a specific part of the big's cells. gene editing is used to cut out the section of dna that is responsible for making that part of the cell. the virus now has nothing to stick on to, so the animals are immune. these pigs are likely to be among the first in a new generation of gene edited farm animals and the technology can be used for more than just disease resistance. groups elsewhere are trying to create livestock which are larger, leaner and more productive. this is a gene edited calf engineered by a us company. the firm's smartphone footage shows she has eight in a coat and sweats more, giving her a

slick code that makes her more resista nt to slick code that makes her more resistant to heat. her breed produces much more milk than african varieties. the edinburgh research as are investigating whether the so—called slick gene could be engineered into higher milk producing western varieties, and introduced into africa. transforming the lives of these smallholder farmers. this man leads the african genetic livestock project in attenborough. he grew up on a small farm in western cameroon. 0ne attenborough. he grew up on a small farm in western cameroon. one year, his father's animals were wiped out by african swine flu. fortunately, his mothers had chickens to sell, in off to pay for his school fees for the year. —— enough. off to pay for his school fees for the year. -- enough. this is what has driven me. i strongly believe that genetics, and all the innovations that exist here in the uk, can actually be used in the context of driving increased

activity in smallholder farming is, including the village where i come from. many campaign groups are opposed to the use of gene editing to boost production and large industrial farms in the west. but some see the technology could be used to safeguard the futures of very poorest in the world, if there really is no other option. the american footballer colin kaepernick has reached an out of court settlement in his legal case against the national football league. kaepernick has argued that nfl club owners conspired not to hire him because he protested against racism and police brutality by taking a knee during the national anthem. he opted out of his contract with the san francisco 49ers and since launching his grievance against the league in 2017 has been unable to find a new team. there are no details of the resolution, as it's subject to a confidentiality agreement. the prize—winning author

andrea levy has died at the age of 62. her novel small island won, among other accolades, the orange prize for fiction, the whitbread book of the year award and the commonwealth writers' prize, and has been adapted for bbc television and the theatre. a reminder of our top story. nigeria's presidential election has been postponed by a week, just hours before voting was due to begin. voting was due to get away in about 90 minutes. now, the chair man of the nigerian electoral commission has said that it was a difficult position, but the delay was necessary to ensure a free and fair vote. more on that story on the website. hello.

judging by the weather over the past few days it looks like spring is in a hurry to start. and, well, apart from the cloud that moved into northern ireland and western scotland, friday brought plenty of sunshine again and the warm spot was in wales. this view from wrexham. it was in rhyll, actually, in north wales, where the temperature reached 17.5 celsius. that's even higher than thursday's top temperature. and over the weekend we are we are still in this lower, mild air heading in from the south. though there are a few weather systems coming our way. so we can't rely on clear blue skies. here's the first week one that's moving across northern scotland, with some outbreaks of rain. another one will come in during sunday. so, for the weekend then, it is still mild. temperatures are above average for the time of year. it will be breezy, especially on sunday. it will be dry for many. though these weather systems will bring a bit of rain, especially to western parts of the uk. and, already, as saturday begins, things are different. not as cold as recent mornings. more cloud around as well. still the leftovers of some overnight rain affecting parts of western and northern scotland before that eases. we're going to keep a lot of the cloud feeding into southern

england. that's going to edge further north. elsewhere it's sunny spells, rather than clear blue skies on another breezy day. so a closer look at things at four o'clock in the afternoon. should start to see some sunshine coming back into the channel islands. could be some coast and hill fog from the thicker clouds in the south, maybe the odd bit of drizzle. cloud increasing for wales, the midlands, into east anglia. but still sunny spells in northern england and a few breaks in the cloud for northern ireland and scotland. best of the sunshine here will be in the east. but cloud thickening in the western isles, again, the northern isles still seeing a bit of patchy rain. could see the odd shower pushing in towards cumbria, lancashire, too. but most places are looking dry. 0vernight we are going to get rid of quite a bit of the cloud, so clearing skies for many of us. though temperatures aren't going down too far into sunday morning. so no issues with frost. then the next weather system i pointed out is starting to bring its wet weather into the west. it's going to weaken as it slides

further east during the day. so we're not going to see too much in the way of wet weather out of this. it is a windier day with this weather system, though, approaching and moving through during sunday. but there is more sunshine around ahead of this system. and it's a fairly narrow one as well. just cloud, a bit of patchy rain working through. clearing through northern ireland. any heavier bursts of the rain, really, into northern parts of scotland for a time. quite windy in western scotland. some gusts up to 50 mph or so. and notice temperatures are just on the up a little bit more compared to saturday. especially, of course, where you get to see some sunshine. eastern part of the uk look mainly dry. not as mild into the start of next week. and still a fair amount of cloud around. this is bbc news, the headlines: nigeria's electoral commission has postponed the presidential poll by a week, hours before voting was due to begin. the commission chairman says it wasn't feasible to proceed as scheduled for "logistical reasons", but the delay was necessary to ensure a free and fair vote. the us president donald trump has declared a national emergency

in an attempt to bypass congress and secure funding for his mexican border wall. democrat leaders have described it as "a gross abuse of power" — and announced an immediate investigation. they say it violates the constitution. relatives of shamima begum — the pregnant teenagerfrom london who went to syria to join the so—called islamic state group, have asked the government to help them bring her home. britain's home secretary has made it clear he'll try to prevent the return of people who've supported terrorist organisations.