welcome to bbc news, broadcasting to viewers in north america and around the globe. my name's tom donkin. the top stories: flying over the front line. we have an exclusive report from mosul where islamic state fighters appear to be using children as human shields. we are now over old mosul where the battle is at its fiercest. there are many civilians trapped in the narrow alleys. waiting and hoping. parents of missing children in colombia help in the search for their loved ones. among the 200 people killed in devastating mudslides. president trump says the united states would be prepared to act alone to counter any nuclear threat from north korea. as campaigners protest at the unsolved murders of mexico's journalists, one newspaper says enough is enough. and coming up... selling for the first time

in hong kong for $86 million. sold for $86 million... an iconic andy warhol painting of chairman mao has been auctioned in hong kong. the bbc has seen evidence of so—called islamic state appearing to use children as human shields in the battle for mosul. it comes as the militants are all but surrounded in the old centre of iraq's second city and there's a growing concern over civilian casualties. bbc persian‘s nafiseh koohnavard and producerjoe inwood were given exclusive access to iraqi helicopter pilots flying over mosul‘s front line. here's their report. far below, a city that was once home to two million people.

we are flying with the helicopters of the iraqi army as they fight the so—called islamic state. we are now over old mosul, where the battle is at its fiercest, as well as the last isis fighters, there are many civilians still trapped in the narrow alleys. and this footage, taken from our helicopter‘s camera, shows the challenges the pilots in mosulface. radio it shows armed men walking through a war zone with children. radio military sources have told the bbc this is the clearest example yet of the use of human shields in mosul. on the ground, major osama explains why human shields are effective. isis use the kids so they escape

from our aircraft because they know we can't shoot on them. they escape by this way. but many civilians have been killed since the beginning of the war. mohammed is one of the most experienced pilots in the army. he says sometimes he has to trust to a higher power. i ask my god, when i shoot every time, when i shoot the fire, "please, god, save the civilian, just kill the bad guys." the battle for mosul is notjust about taking back a city. it's about regaining the trust of its people. every civilian casualty undermines that work and so the iraqi forces have to take their time. translation: we have two reasons for slowing down. one is the civilians, the second is that we have got

to old mosul. it's a difficult part of the city to fight in, full of narrow streets with small houses. it's ancient and crowded. back above mosul, the pilots circle, looking for targets. they spot a group gathered in an alley. the men have seen us too. they shoot into the sky. the helicopter returns fire. it is clear why air power has been so vital. mosul is now surrounded but the battle for the old city will come at a cost. much of it paid by the civilians still trapped inside. nafiseh kouhnavard, bbc news. back on the ground, the battle

is still going on in residential streets of the city. one of the challenges is stopping the militants from detonating car bombs. the bbc‘s defence correspondent jonathan beale is in mosul. just building barricades on these streets, which have recently been liberated from so—called islamic state. to prevent car bombs, this is one that didn't go off around the corner, they managed to kill the driver before he detonated it, but this is just a few hundred yards from the front line now. we can occasionally hear gunfire from so—called islamic state. now, this is the start of the old city. as you can see, the streets are wide enough to drive armoured vehicles up, trucks and the likes. but when they get into the old city itself, there are narrow alleyways where they won't be able to drive armoured vehicles at all and the fighting there is going to be much, much harder.

rescue teams in colombia are continuing to search through tons of mud and debris for anyone who might have survived the devastating mudslides in the south of the country. more than 200 people have been killed but, with many others injured or missing, the country's president says the final death toll is impossible to predict. the mud engulfed the town of mocoa, burying entire neighbourhoods, and further bad weather is now hampering the rescue effort. richard lister reports. mocoa is a place of mud and misery. when the rolling wall of water and debris rushed through here on friday night, it swept away houses, cars, trees and people. whole families died here. the painstaking search for survivors is continuing. rescue workers moving quietly through flattened neighbourhoods,

hoping for sounds of life in the wreckage. nothing here. with every hour that passes, hopes of finding more people alive diminish. within hours of the deluge, message boards went up, listing the dead and missing. many of those unaccounted for are children. "we are searching for a baby", she says. "a little baby. we can't find him anywhere". this man has lost his daughter. "i hope somebody has her", he says. "she's called luisa". closest to the river, the streets are now boulder fields, full of people trying to retrieve what they can of their lives. the shock of this disaster is still sinking in. in the worst affected areas, people struggle to find the places where their houses once stood. the rains that caused this flood

were unusually heavy, but deforestation upstream played a part too. emergency teams have been working here night and day, since the river burst its banks. more help from the government is on its way. translation: there are ten water tankers here and ten more are on their way. we're also bringing water purification equipment and generators to ensure there is a clean water supply for the people. for now, though, many people in this town of 40,000 still lack access to power and fresh water. the homeless need housing. the infrastructure needs to be restored and the wreckage cleared. deep in the amazon basin, mocoa was hard to reach before. now, with roads and bridges washed away, the challenge is even greater. richard lister, bbc news. president trump says the united states would be prepared to act alone to counter the nuclear threat from north korea. speaking to the financial times

newspaper, mr trump said: north korean missile tests are expected to be high on the agenda in talks later this week with his chinese counterpart, xijinping. i spoke with james person from washington's public policy think tank the wilson center and asked him what he made of president trump's comments. president trump's statement is in many ways trying to get china to step up its game a bit before president xi's upcoming visit to washington. we have long overstated china's ability to exercise political influence over north korea. there is no doubt that china today has greater leverage over north korea because of its economic assistance to the country. but china has different influence on the peninsula and it is not willing to use that leverage to bring north korea to its knees, for example. which is what we want, to force north korea to abandon its nuclear ambition.

in fact, there's a profound sense of mistrust at the basis of the relationship that limits china's ability to really influence north korean policies. there's a sense in north korea that china's been overly interventionist and less than respectful of korean sovereignty over the past several decades. so if this is some kind of warning to china before the two leaders meet, do you think it will work and do you think china will be more motivated to act after these words from president trump? well, one would hope. there are some reports that in fact china's supposed... the cut on coal imports for 2017 are not really put into effect. one would hope that china would in fact take these sanctions more seriously. the us could actually do a lot more. in fact, i think the us

underestimates its own leverage over north korea and again, has overstated china's ability to handle the problem. this has been our default policy for the past three plus decades, to essentially outsource the north korea problem to china. the us really needs to do much more. in some senses, this is actually a very sensible thing of president trump to consider doing more. the us stepping up its own game. in other news: in ecuador over 90% of the votes have been counted in the country's presidential election, the electoral council says the leftist candidate lenin moreno is ahead of his right wing rival guillermo lasso with 51.05% of votes. both candidates have claimed victory. the serbian prime minister, aleksandar vucic, has won a clear

victory in the country's presidential election. mr vucic said serbs had voted to continue to work towards greater ties with the european union while maintaining close relations with china and russia. russian police have detained at least a0 protesters in moscow during a demonstration against government corruption. this latest protest was much smaller than a similar one last weekend when thousands demonstrated in the capital and several other russian cities. earlier i spoke to lina garcia, a co—ordinator from the colombian red cross, about the latest developments in the search and rescue operation. the colombian red cross has deployed 149 volunteers and employees in order to attend the emergency. up until now, the official information given by the colombian government is 210 corpses found. 112 corpses have already been identified. we have 266 wounded. 300 families have actually been

affected by the emergency and approximately 220 missing persons. the colombian red cross has a service called restoring family links and up to now, we have had 326 persons requesting this service. up to now, we have been able to close nine of the 326 cases of restoring family links. while us, as the colombian red cross, the services we are providing to our communities are health services, psychosocial support, as i said already, restoring family links. we are supporting the government

with water purification plants in order to provide potable water for the communities. a regional newspaper in mexico says violence against journalists and the lack of punishment for those responsible is forcing it to close down. norte de ciudad juarez said sunday's edition would be its last after a journalist who worked for the paper was shot dead last month. greg dawson reports. the final headline was a simple one — "goodbye." above the door of the norte newspapaer building, a black ribbon to mark the murder that has prompted this closure. miroslava breach reported for the paper on organized crime and drug trafficking in ciudad juarez. last month she was shot eight times outside her home. the gunman left a note saying,

"for being a loudmouth". last week, friends and colleagues came together in mexico city to commemorate her and two other reporters. all three killed in the same month. campaigners claim more than 100 journalists have been murdered in the country since 2012. the majority of cases are unsolved. translation: three colleagues have been killed, others have been injured and the authorities do nothing. regrettably the inaction in any state, in a country in which journalists are injured is plain — nothing happens. located on the border with the united states, juarez has for years been one of mexico's most violent of cities. the work ofjournalists here often involves investigating the drug cartels competing for routes across the border. but the newspaper's owner says, without the protection and freedom they need, it is a story they are no longer able to tell. greg dawson, bbc news.

stay with us on bbc news, still to come: tributes are paid to darcus howe, who's died aged 7a after a lifetime campaigning for civil rights. the accident that happened here was of the sort that can at worst produce a meltdown. in this case the precautions worked, but they didn't work quite well enough to prevent some old fears about the safety features of these stations from resurfacing. the republic of ireland has become the first country in the world to ban smoking in the workplace. from today, anyone lighting up in offices, businesses, pubs and restaurants will face a heavy fine. the president was on his way out of the washington hilton hotel, where he had been addressing a trade union conference. the small crowd outside included

his assailant. it has become a symbol of paris. 100 years ago, many parisians wished it had never been built. the eiffel tower's birthday is being marked by a re—enactment of the first ascent by gustave eiffel. this is bbc news. i'm tom donkin. the latest headlines: the bbc sees evidence of so—called islamic state appearing to use children as human shields in the battle for mosul. president trump has said the united states would be prepared to tackle the growing nuclear threat from north korea with or without help from china. gordon chang is a china analyst and the author of ‘nuclear showdown: north korea takes on the world' joins me now from newjersey. tributes have been paid to the british civil rights campaigner darcus howe — who has died at the age

of seventy four. the writer and broadcaster campaigned for black rights and against racism for more than 50 years. our correspondent elaine dunkley looks back at his life. in the fight against police brutality and racism, heroes of a struggle were born. darcus howe, a prominent figure in the british black panther movement. in the 1970s, he was arrested, charged with inciting a riot with a group of activists protesting about police harassment at the mangrove restaurant in notting hill. it was a completely non—event. until you looked around and saw about 600 police. and we thought, hell, what's this? at the trial, all nine were cleared. the mangrove nine became a landmark case, exposing heavy—handed police tactics towards the black community. in 1981, darcus howe organised a 20,000 strong black people's day of action in protest over the police handling of the investigation into the new cross fire in which 13 black teenagers died. darcus was a fearless warrior.

he helped to establish a tradition of black self organisation to tackle racial oppression. darcus howe, at times controversial and confrontational. you are not a stranger to riots yourself, i understand, are you? following the london riots in 2011, there was this heated exchange. i have never ta ken part in a single riot. i have been on demonstrations that ended up in a conflict. and have some respect for an old west indian negro and stop accusing me of being a rioter. at the commonwealth institute, an art exhibition is on show. as well as an activist, he was a well—known broadcaster and writer. always formidable and fearless. for more than 50 years, darcus howe was at the forefront of the fight against racism. back to the comments by donald trump

that he would be prepared to tackle the nuclear threat from knocks and —— north korea with or without the help of china. gordon chang is a china analyst and the author of ‘nuclear showdown: north korea takes on the world' joins me now from newjersey. thank you forjoining me. is there too much made over china's influence over north korea or do they really have the leverage that the us needs? they certainly have the leverage. about 90% of north korea's foreign trade is with china. china provides diplomatic support and have actually been given technical support to its ballistic missile ‘s programme, its nuclear weapons programme and there is china's interest in north korea's other illicit activities. clearly

china has scope to have influence but it's not doing so. policy options have effectively been rushed through in time for president xi jinping's visit, sources have said. while the issue with north korean has been brewing for at least three presidencies, donald trump is seeing it as an imminent threat? it is because north korea already has three missiles that can hit the lower 48 states. now, the first one has not been tested at full range. the other two have not been tested at all but they are based as —— based on proven technologies. they will probably work. it will be about four years or so before north korea will be able to make it to those long—range missiles but it is making fast progress as specially because

it is getting technical help from china. donald trump seems to be setting some distinct deadlines to see some action with north korea. is it your view that the obama and bush administrations gave north korea or indeed china too much slack to act on their behalf? absolutely. the united states have pursued policies that haven't worked. they have been doing that over the course of two or three decades, depending on how you view history. clearly, the united states has been very indulgent, not only towards the north koreans but especially towards china because we look to china to solve this problem for but also we want to integrate china into the international system and gave it a much higher rarity than disarming north korea. this is a result of bad and american policy and then trumped, whatever people might think of him, they put trumpet into with physical position. -- they

put trump into a very difficult position. an andy warhol portrait of chairman mao has been sold at auction in hong kong, to an asian collector. but the piece didn't quite manage to generate the frenzied level of bidding that had been anticipated. our hong kong correspondent juliana liu was there. 80 million... 82 million... at 86 million... and selling for $86 million. sold! when the hammer came down, this iconic painting of chairman mao was sold for $11 million. it was the first time a warhol depiction of the chairman had been offered at a public auction on chinese soil. the price, though, unexpectedly fell short of its lowest estimate. the absolute star of the auction was this piece by andy warhol. but the sale disappointed, the painting failed to fetch as much money as the auction house had originally expected.

critics say that it could be because the chinese art world is recovering from a graft crackdown started by the chinise president, xijinping. political imagery is highly controlled on the mainland. four years ago, pieces from this series of paintings were banned from an exhibition in beijing and shanghai. the mao pieces were among andy warhol's most acclaimed works. he began the series in 1973, after the us president, richard nixon, made a historic trip to china, to meet the chairman. at the time, mao zedong was one of the world's most famous people. the painting was won by a collector in asia, so it is a homecoming, of sorts, for this famous portrayal of a chinese icon by a western artist. juliana liu, bbc news, hong kong. now for something you don't see every day. this a 44 metre high factory chimney in the city of roosendaal in the netherlands. here it is being moved

from one site to another. now, we've sped up the process for you — that's because the distance of 450 metres took the chimney 4.5 hours to complete. the structure is seen as an icon of the city and is part of the old philips factory. the company sees the chimney as an important industrial heritage site. here in the uk, there were mixed fortunes in the annual oxford and cambridge boat races earlier. in the women's competition, cambridge stormed to the finish line in 18 minutes and 34 seconds — beating the record set in 2015 by more than a minute. for the men, oxford made it four wins in five years, beating their opponents by just over a length. a reminder of our top story: that is it from me and the team. stay with us on bbc news. good morning.

if you like your weather dry and sunny, you were very happy with the first couple of days of april. in fact, we had sunshine topping and tailing the country. just look at this picture from sunday in south—west scotland. a beautiful day here. similar story in the london area, as well, where you can enjoy the spring blossom. it was the warmest place in the country with 17.2 celsius in st james's park. now, our week ahead will be a mostly dry one. just a little bit fresher, though, and i suspect through the night, some chilly nights will come. a touch of light frost not out of the question. high pressure hanging on in there in eastern areas, but out of the west, these are these fronts pushing in. they will not bring significant rain but will bring a change through northern ireland and western scotland, as we go through the morning, eventually into western fringes of wales in the south—west. ahead of it, though, any early—morning mist will lift away for sunshine.

so, by the middle of the afternoon, eastern scotland should cling on to the dry weather, but elsewhere, those weather fronts bringing some showery outbreaks of rain into scotland and into northern ireland. ten or 11 degrees the high. eventually pushing into the west of wales. more cloud, certainly, through the lake district, wales, and down into cornwall. but to the east, we should see highs of 17 degrees inland. maybe if we keep a little bit of coastal cloud cover it could stay a little cooler and disappointing. our weather fronts continue to push across from the west through monday night into tuesday morning. by now, a band of weak spits and spots of rain, really, just pushing into the south—east. but it keeps a fair amount of cloud first thing on tuesday morning. that will clear away into the afternoon. slowly brightening up from the west, breezy with a scattering of showers to the north and west of scotland. high expected on tuesday, though, temperatures in scotland fresher on tuesday, at about eight to 15 degrees. so as we move out of tuesday afternoon into tuesday night, there's some premier league matches. it looks as though it will be a dry affair for all the kick offs. just that little bit fresher. but all in all, not too bad, if you are going to watch those

matches. and a similarfor the scottish premiership — dry, with temperatures over eight or nine degrees as a high. talking of high, stays with us, really, through the middle of the week, building from the south—west. all the while, these weather fronts toppling off the top into scandinavia. a bit of a stronger wind into the far north and a slightly fresher direction, but this does mean a fair bit of dry, sunny weather on offer for many. very pleasant indeed. take care. the latest headlines from bbc news. i'm tom donkin. the bbc has seen evidence of so—called islamic state appearing to use children as human shields in the battle for mosul. it comes as the militants are all but surrounded in the old centre of iraq's second city and there's a growing concern over civilian casualties. president trump has indicated that the united states would be prepared to act alone to counter the nuclear threat from north korea. in an interview with

the financial times newspaper, mr trump is quoted as saying the us could take unilateral action if china did not put more pressure on pyongyang. more than 200 people, many of them children, have died in landslides in colombia's southern city of mocoa. the colombian army and emergency services are helping in the search. but with many others injured or missing, the country's president says the final death toll is impossible to predict. time now for hardtalk.