this is bbc news. i'm kasia madera. our top stories: a wave of destruction captured on camera — dramatic new footage shows the momenta dam collapsed in brazil. at least 110 people are dead and more than 200 still missing. the question everyone here is stunned by is how this could ever have been allowed to happen. facebook loses one of its key fact—checking partners, prompting questions about how committed it is to rooting out fake news. we have a special report from venezuela, where opponents of nicholas maduro say they've been detained and tortured in the past few days. translation: they put a gun in my mouth and they cocked it. they said they want answers fast and that they loved to see people suffer.

and as cory booker becomes the latest democrat to announce he's running for the us presidency — we'll take a look at what's becoming a very crowded field for the 2020 election. hello and welcome to bbc news. we begin the programme with dramatic footage showing the moment a dam burst in brazil, releasing millions of tons of mining waste that engulfed nearby buildings. at least 110 people are now known to have died in the disaster, which happened in the state of minas gerais last month. hundreds of people are still missing. 0ur science editor, david shukman reports from the site of the dam, in south—east of brazil. first, a long cloud of dust, then a nightmare vision of an unrelenting torrent of sludge, the waste from decades of mining racing towards hundreds of unsuspecting people down below.

the catastrophe unfolded a week ago, but only now has this video come to light, adding to the sense of loss, and of outrage. and difficult for you. this red cross volunteer, henato silveira, leads me to the edge of the disaster zone. seis corpos. six bodies. he alone has found six bodies. any hope of reaching survivors in this endless sea of mud was quickly dashed. emergency workers are now scouting for any signs of bodies from the air, and they are picking their way over this horrific landscape. we spotted this search team with a sniffer dog in the distance. by the time the wall of mud reached this point, it had already overwhelmed the cafeteria where the miners were having lunch and destroyed the offices of the mine itself, before arriving here, tearing through a hotel and holiday chalets, before surging on over that ridge in the distance and down into the valley beyond, where it caused yet more destruction.

and the question everyone here isjust stunned by is how, in a big, modern, growing economy, this could ever have been allowed to happen. investigators are now on the scene. the dam holding back the waste was owned by one of the world's largest mining companies. it was inspected only last year. we find a local man, leandro gil, praying for friends lost in the mud. "unfortu nately", he says, "someone just thought about himself. he didn't protect the dam properly. so, after years and years, that's now been revealed." a special mass, seven days since the disaster. there is grief and anger, and the demand for answers will only grow. david shukman, bbc news, in brazil. some awkward news for the social media giant facebook, after one of the companies it brought in to sift out fake news

said it was pulling out of the deal. the company concerned is snopes, it was one of more than 30 fact—checking operations working with facebook. but there had been reports of frustrations that facebook had been less co—operative than hoped with its partners. in announcing its withdrawal, snopes said... facebook also released a statement, stating... 0ur north america technology reporter dave lee is in san francisco and says this is a very awkward situation for facebook. snopes it is seen as one of the leading fact checking organisations

on the internet so for them to be pulling out of this field is pretty embarrassing for facebook and could harm the view it is trying to launch and try to get on top of it misinformation problems. snopes has been working with facebook since late 2016. in their statement today they did allude to the fact that financially it could be difficult for them. in 2017, for example, facebook the payjust $100,000 to snopes, which is less than the average wage of a single facebook employee. there were suggestions that snopes was trying to push facebook ‘s hand to say you need to pay more money for the service but facebook is saying it is one of many in fact checkers it is working with and the control of misinformation

has not too severely affected. an interesting point because it is one of the many, many companies doing this on behalf of facebook? yes, it is. facebook has been under great pressure to get on top of notjust physical misinformation from russia and more recently you run but also generalfake news. and more recently you run but also general fake news. —— and more recently you run but also generalfake news. —— iran but also in the election from 2016 and the midterms. the company figured the best way towards to enlist a company outside the company. facebook itself has long been uncomfortable in trying to make those judgements themselves. 0ne trying to make those judgements themselves. one of the complaint these companies are seeing to be having is that facebook is not open about what is on their platform and the scale of what they face. this

friction has been bubbling up, i think it is fair to state and this move from snopes is the biggest indicator that it is not as sound as it could be. could the world be on the verge of a new nuclear standoff? that's the question being asked, after the us suspended a landmark deal, which has been in force for more than three decades. it's accusing russia of breaking it. the agreement in question outlaws the use of intermediate range nuclear missiles stationed on land. washington says moscow has been breaking it for years, something russia denies. laura westbrook reports. in 1987 us president ronald and soviet leader mikhail gorbachev signed the treaty. it led to hundreds of missiles in both countries being destroyed. three

decades later, us secretary of state made this announcement... russia has jeopardised the us security interests and we can no longer be restricted by the treaty while russia shamelessly violates it. nato agrees with the decision by the united states. we can -- continued to call on russia to find a viable way. we do not want a new arms race. this was not unexpected. for years america has been consigned about russia ‘s testing and deployment of cruise missiles which it says breaches of the treaty. the recite other countries, including china, are not tied by the court. and now the treaty is suspended. the us could pull out formally in six months but gave russia a final chance to save the deal. months but gave russia a final chance to save the deallj months but gave russia a final chance to save the deal. i hope we are able to get everybody in a big and beautiful lawn and a new treaty

would be much better but certainly i would be much better but certainly i would like to see that. for its part, the kremlin said this was a political decision. russia denies the b cell in question is in violation of the treaty. this was iran ‘s response... this was the image that let it be world know the cold war was coming to an end, 30 years later many are concerned about the future of nuclear arms control. let's get some of the day's other news: the court of arbitration for sport has banned 12 russian athletes for doping. they include the london olympics highjump gold—medallist ivan uskov and svetlana shkolina, who won gold at the 2013 world championships. both were given four year bans. the americans who won silver will inherit gold. the offences of all 12 athletes date back to those sporting events. the mother of a 3—year—old girl

in britain has been found guilty of female genital mutilation, the first person to be convicted of fgm since it was made an offence more than 30 years ago. the woman, originally from uganda, was arrested in 2017 after taking her heavily—bleeding daughter to hospital. the italian authorities have impounded the last charity rescue ship operating in the central mediterranean. the sea watch three was detained after being allowed to disembark the sea watch iii was detained after being allowed to disembark 47 migrants in the sicilian port of catania. italy's populist government has been trying to stop humanitarian groups from bringing rescued migrants ashore. authorities in the united states fear the death toll linked to the deep freeze may rise. at least 21 people have died during the cold snap. the mercury plummeted to —30 degrees celsius in places like chicago but the icy conditions

have started to ease. emergency services are bracing for the ice and snow to melt, increasing the chance of urban flooding and mudslides. venezuela's opposition leader juan guaido is calling for the biggest mass protests in the nation's history this weekend as he tries to force president nicholas maduro from power. the opposition are demanding new elections, to end the political and economic chaos engulfing the country. human rights lawyers have told the bbc there's been a wave of political arrests, with almost 1,000 people detained in recent days. the government denies it tortures prisoners. but our international correspondent 0rla guerin has heard a harrowing account from one women, who says she was beaten and abused. you may find some of 0rla's report upsetting. under darkened skies, caracas waits.

some here hoping for a modern day liberator to replace president nicolas maduro. but those who dare to oppose him can expect to pay a price. almost 1000 people have been detained in the past ten days. we are on our way now to meet one of them. she's a young woman who we can't identify for own safety. she's just been released and she has a harrowing story to tell. she says she was held for eight days in this building, the headquarters of the military police. they interrogated her about a relative, a military officer suspected of plotting against the president. translation: they tortured me. they put a plastic bag over my face and choked me. then they put my head in a bucket of water to try to drown me.

i fainted and they beat me to wake me up. they put a gun in my mouth and cocked it. they said they wanted answers fast and that they loved to see people suffer. their boss told them all to rape me. they lifted my shirt and took off my bra and they touched me. did you think that you might be killed? translation: yes, because they were constantly saying it. they said they were going to kill me and throw me in the river. they said, "we are the government and nobody can do anything against the government". leading human rights lawyer, alfredo romero is struggling to keep up. he says the government is in overdrive, trying to silence dissent. now we can talk also about generalised persecution, generalised detentions. that they detained anyone in order

to intimidate people and produce what they are producing, this fear of protest. that is what is going on. but some, like federica romer, a politics student, are determined to keep up the fight. she says being a mother to 6—month—old carlota means she has to protest. this is for her, you know? this is for her. before i had her, ifelt invincible and i didn't care. and now that i have her, of course i'm scared to go out. i'm terrified. but this is absolutely for her, you know? because she is the next generation of this country. they are the ones who are going to hold this country up. federica is preparing to go back out on the streets tomorrow at a mass demonstration called by the opposition, gas mask at the ready. 0rla guerin, bbc news, caracas.

stay with us on bbc world news, still to come: what's it like to be a teenager in uganda? in the latest in our series on 17—year—olds, we spend a day with joy from kampala. this is the moment that millions in iran had been waiting for. after his long years in exile, the first hesitant steps of ayatollah khomeini on iranian soil. south africa's white government has offered its black opponents concessions unparalleled in the history of apartheid. and the anc leader, nelson mandela, is to be set free unconditionally. ..four, three, two, one... a countdown to a critical moment.

the world's most powerful rocket ignited all 27 of its engines at once. and, apart from its power, it's this recycling of the rocket, slashing the cost of a launch, that makes this a breakthrough in the business of space travel. two americans have become the first humans to walk in space without any lifeline to their spaceship. one of them called it a piece of cake. thousands of people have given the yachtswoman ellen macarthur a spectacular homecoming in the cornish port of falmouth, after she smashed the world record for sailing solo around the world non—stop. this is bbc news, the latest headlines: dramatic new footage has emerged, showing the moment a dam collapsed in brazil. at least 110 people are confirmed dead. facebook has lost one of its key fact—checking partners, the news website snopes. the democratic field to take

on president trump in the 2020 elections is getting more crowded by the day. the latest entry is senator cory booker from newjersey. he's the fourth senator on the current list of candidates, and the second african—american. booker is hoping a message of optimism and unity will set him apart. jane 0'brien reports. in america, we have a common pain. but what we are lacking is a sense of common purpose. cory booker, the charismatic senator from newjersey has been positioning himself for a presidential bid for some time. and like many of his rivals, his official declaration has come early. he portrays himself as somebody who can bridge america's eligible, racial and economic divides, making his formal ditch outside his home in a low—income neighbourhood.” believe in the american people, i

think they will look to the american democratic party for leadership, i believe we are going to consolidate this country against the politics of hate, politics of division. in a crowded field that now includes four senators, name recognition is key. the candidate must also make clear their differences. i imagine that their differences. i imagine that the crowded democratic field of presidential aspirins will be a sacking each other‘s records or lack thereof, so we will be sitting back with copious boulder popcorn watching that. but look who has made civil rights and racial injustice the cornerstone of his political career shows no sign of mudslinging. at least not yet. how is my hair? is there anything hanging out of my nose? that is a real friend who tells you to truth. that is cory booker with senator kirstenjill brand, one of the record number of women throwing their hat in two the ring. i am cory booker, one of kirsten gillibrand's best friends in

washington. and there are joe biden, ito o'rourke and bernie sanders. the former vice president has yet to declare that he is the £800 gorilla in the room. he is known, he is liked, and his moderate. and in a showdown with donald trump that might give him the edge. earlier i spoke to daniel lippman, co—author of the daily newsletter politico playbook, and he told me that although mr booker has a remarkable story, voters will be waiting to see if he's the real deal. there is a great movie called street fight that was nominated for an 0scar, that tells the tale of cory booker running firm air of newark, newjersey, more than a decade ago. —— from there. he what lost the first time, won the second, and he likes to brag to people boast that he is the only us senator that goes back to a low—income neighbourhood

every weekend in newjersey, he is trying to stay true to his roots, and his constituents love them because he is the type of senator, and he was that mayor who would shovel snow, repairs potholes, and he was that mayor who would shovelsnow, repairs potholes, he and he was that mayor who would shovel snow, repairs potholes, he is very in touch with real, everyday problems, not just the very in touch with real, everyday problems, notjust the rising about academic solutions. but can he elevate that onto a national platform than? he is well known among his local constituents, but when it comes to the bigger picture, can he capture the mood of the nation? there are so many different candidates that it is going to be ha rd candidates that it is going to be hard for him or anyone else who is not ajoe hard for him or anyone else who is not a joe biden type to really cut through and deliver their message in a way that residents for those democratic primary voters —— residents. another question he faces

is, he is obsessed with the term love, he uses it all the time, and thatis love, he uses it all the time, and that is great, but what democrats wa nt that is great, but what democrats want is a fighter who can take it to donald trump, and do well in those debates that are going to be critical. and if he is seen as being too weak, or not enough of someone who is really going to go hard against trump, then democrats made inc that he should wait his turn —— may think he should wait his turn or maybe be vice presidential candidate. if joe maybe be vice presidential candidate. ifjoe biden does maybe be vice presidential candidate. if joe biden does declare as he most probably will do, if and when he does come into the running, is hea when he does come into the running, is he a sure thing in that case? he is he a sure thing in that case? he is not the sure thing because it is such a big field. michael bloomberg, the former mayor of new york city will also be a front runner, he has said he is going to spend hundreds of millions of dollars there is a

story in the atlantic about how he is going to build a huge data machine to try and get as many voters on his side as possible. he has a pretty formidable team. but it is really a jump ball with almost a dozen candidates about to enter the race, and more coming soon. no wonder is a sure thing right now —— no—one is sure thing. people are trying to look at who is the most delectable, also who has great ideas on who will move the country forward. kamala harris has got a little heat from the centre of the party, who says that medicare for all would not be a good option to the country. apple says it has found a fix for a bug that let iphone users eavesdrop on other facetime users, even when the person they called did not answer. the flaw meant the microphone on the recipient's phone was activated. technology journalist will guyatt says apple should have done more. they haven't been quick enough, it

is incredibly embarrassing, there is almost a billion devices using ios, and if we follow this story through, and if we follow this story through, a young child and his mum in the us actually tried to report this to apple at least a week before they recognise there was an issue. they announced the fact that they knew there was a problem on tuesday, and it has taken over a week about to arrive. what's it like being a teenager in africa? the bbc spent a day with seventeen—year—old joy in uganda where he showed us what it's like to grow up in the capital kampala. his story is part of a series called "being17". lets have a look. uganda is different from other places. when you tell someone you

have school six days a week, they are like, what? i want to become an architect, and i cannot achieve that do —— achieve that dream if i do not go to school. i am done with maths already, i am going to technical drawing. it is one of my favourite subjects. it starts here and go to this part. uganda is a country with many different tribes, we are very cultured, and there are different people from different backgrounds, and all accepted the way they are. after school, i go to abandon a this, with my church. —— i go to band practice. at the moment we are doing mostly covers but i am working on some original music over the yea rs on some original music over the

years uganda has changed, right now there are more opportunities to women in school and workplaces. #me women in school and workplaces. # me love the way you handle me, me love the way you fight for me, me love the way you fight for me, me love the way you fight for me, me love the way... the church and my spiritual life are very important to me. writing music is fun to me, and i hate being bored so is fun to me, and i hate being bored soido is fun to me, and i hate being bored so i do all these things to keep active. i would like to go and study abroad, but then eventually i would come back here, i would come back and stay in uganda. it is a nice place to be, generally. thank you to i°y place to be, generally. thank you to joy for letting us to spend the day with him. friday was another day with severe

transport disruption due to heavy snow. it was across central and southern england that had the worst of it, the billy stretch is of the m3 towards the basingstoke area. we also had trouble is around the m2 in kent as well late in the day. some of those problems were pictured from this area overlooking the m3, you can see how horrendous that conditions look there on the main carriageway, completely covered in snow. transport disruption has been a factor of the forecast through friday, and again into saturday as well, with the risk of some snow still around, but ice as well fairly widely. looking at the weather picture over the next few hours, the snow that we have across south—east england is coming confined to kent before easing away. they will be wintry showers across the eastern side of scotland into eastern england, wherever those showers fall of course that adds to the risk of ice with the widespread and sharp

frost once again. the forecast survey is there will be more wintry weather around, after a cold and frosty start, i see as well, we will seek entry showers trickling down the eastern coast, probably saying quite cloudy for part of the morning across the maybe with some flurries, but nothing too heavy. some showers affecting western wales but they will ease with time. we will see a few showers coming in across the north—west of northern ireland into western scotland. the showers are a bit of a mixture here with some rain around sea level, we could see some sneak —— sleet and snow mixed in. saturday a decent day with some bright or sunny spells after that cold and icy start. images will be struggling once again, looking at a cold daytime of your that goes into saturday night are clear skies leading to a sharp fall in temperature is the most of the uk. -6 temperature is the most of the uk. —6 in newcastle, there is the risk

of some icy stretches, but further west we will see some cloud thickened as the weather system approaches of the atlantic the sunday. this is going to bring another spell of wintry weather. we could see a few more centimetres of snow, targeting possibly the high ground in northern ireland, but the far north of england and scotland could see maybe 3— six centimetres, but there is a tendency at lower levels will that's no transition back to reign as mild air tries to move in from the west. 5—61; glasgow and belfast. into next week it is all changing, it turns more mild but there will be some heavy rain around as well and it will often be win the. —— the windy. this is bbc news, the headlines: dramatic new footage has emerged of the moment a dam collapsed in brazil, killing at least 110 people. around 200 more are still missing, after the wave of mud and slurry surged down the valley. the fact—checking website snopes has said it's cutting ties with facebook. media reports last year suggested that fact checkers working with facebook have been frustrated

by its lack of transparency. the united states has suspended a landmark nuclear weapons treaty with russia, which has been in force for three decades. announcing the move, secretary of state, mike pompeo, said russia had six months to demonstrate it was complying. the newjersey senator cory booker has confirmed that he's running for the democratic nomination for president. he joins a list of several high profile democrats who've announced their candidacy for the 2020 race. a woman from east london has become the first person to be convicted of female genital mutilation in the uk.