Laura Bicker
China correspondent

Image source, Reuters

Gyirong port has become the focal point of the disaster for rescue teams in China.

Dramatic footage from surveillance cameras appeared to show the grand building marking the border being swept away by torrents of mud and water as hundreds of people ran for their lives.

The building sat in the deepest of the five Himalayan valleys and had become a thriving hub after an earthquake in 2015 damaged other routes.

It was the main passageway for tourists making their way between Nepal and Tibet. More than 100,000 people passed through in the first half of this year and it handled more than 30% of all Chinese-Nepali trade.

Some social media users in China are questioning why the government decided to place such an important port in a deep valley in a geographically unstable region.

Last year, 17 people were killed after severe rainfall led to a massive mudslide and triggered flash floods.

However, history plays a part especially in a mountainous region where only valleys offer a passageway through the Himalayas between the two countries. For more than 1,300 years this port was used by nomadic herders, Nepali traders and local villagers.

Katie Williams
Live reporter

Image source, Reuters

Rescuers are in a race to find survivors after devastating flash floods hit the Nepal-Tibet border on Wednesday.

The full scale of the disaster is still emerging, but officials say at least 332 people have died in Nepal while more than 900 are missing - the majority foreign citizens.

In Tibet, three have been confirmed dead and at least 558 are missing, according to China's state broadcaster. It is unclear whether the missing figures overlap with Nepal's.

An experienced mountaineer who has previously witnessed flash floods in Nepal tells the BBC he can't believe how "explosive" and "violent" the disaster was.

Two sisters whose parents travelled to the region from Texas tell the BBC they "just love them a lot and want them to come home".

Information on what triggered the flooding has been gradually emerging. Experts now believe "glacial collapse and debris flow" was the cause rather than an earthquake.

And experts say there are concerns about possible "second and third waves", potentially caused by debris in rivers.

Justin Rowlatt
Climate editor

Image source, Getty Images

It is worth noting a parallel with the 2015 Langtang disaster. This latest event also appears to have originated on Langtang Lirung, the mountain above the valley.

In 2015, the earthquake triggered a vast avalanche of ice, snow and rock from the mountain that destroyed Langtang village below.

I was the first journalist to reach the aftermath - at least 215 people had died and the village was almost totally covered in rock and ice.

This latest collapse appears to have come from the north face of Langtang Lirung, rather than the south side involved in 2015.

Justin Rowlatt
Climate editor

It is still very early days and scientists are trying to piece together exactly what happened. Satellite imagery and seismic analysis point to a huge avalanche of ice and rock crashing into the valley and triggering the flood.

It is too soon to determine what role climate change played, although researchers acknowledge it could have contributed.

Rising temperatures are causing mountain glaciers around the world to retreat and permafrost (the frozen ground below) to thaw - potentially destabilising steep slopes by weakening the ice that helps bind fractured rock together.

Scientists say these kinds of high-mountain hazards are becoming an increasing concern across the Himalayas.

Mohd Farooq Azam, a specialist with the International Centre for Integrated Mountain Development (ICIMOD), an intergovernmental scientific institution, said the increasing frequency of hazards in the cryosphere - or the frozen parts of the Earth - "is becoming more visible than ever before.

The pace of change is so rapid that current efforts are struggling to keep up".

We'll bring you more from our climate editor in our next post.

Deluge submerges valley in minutes, video showspublished at 11:43 BST

11:43 BST

By Adam Durbin and Benedict Garman

Verified videos showing the sheer scale of yesterday’s flooding along the Trishuli River continue to emerge on social media.

One video BBC Verify has checked shows an almost incomprehensible deluge of water, submerging buildings and fields near the town of Trishuli in a matter of moments.

Here is what the start of the four-minute video looks like, as the flood begins to surge down the river:

Image source, X

About three minutes later, the water has risen metres and filled the valley:

Image source, X

Azadeh Moshiri
Reporting from Nepal

Image source, AFP via Getty Images

Rescuers are struggling to reach areas struck by flash flooding on the border of Nepal and Tibet.

As we landed, we spotted an Indian plane delivering emergency supplies, which is just some of the aid pouring in.

The region where the disaster happened is popular with pilgrims and trekkers, with tens of thousands of tourists making their way from Nepal to Lake Mansarovar every year.

Survivors are sharing harrowing stories of friends and family swept away by the flood and torrents of mud.

Hydropower facilities have been damaged, and there are fears for the workers inside them, many of whom are now missing.

Experts believe a glacial collapse and debris may have triggered the flooding. There are warnings that some debris washed away into the river systems which could trigger more flooding.

But there is also hope. Rescuers are pushing to reach the hardest-hit areas, and have managed to rescue dozens of people so far.

Nepal police have just issued another update, saying 332 people have died as of 15:50 local time (11:05 BST) on Thursday following the floods.

It came shortly after an earlier update at 14:30 local time (09:45 BST), which placed the death toll at 289.

Nepal's National Disaster Risk Reduction and Management Authority says 910 people are missing and remain uncontactable following the floods.

This includes 517 foreign citizens, 44 members of the Nepal Army and 28 Nepal police officers.

It adds that 258 bodies have been recovered so far, while 351 people have been rescued.

In our latest update, we reported figures from Nepal police saying the death toll has reached 289. Both organisations have been providing separate updates on the rescue operation as it develops.

Nepal police says in its latest update that 289 people have died as of 14:30 local time (09:45 BST) on Thursday.

Image source, Reuters

Prime Minister Andy Burnham says the UK has pledged £5 million to help with the response effort in Nepal following the flash floods on Wednesday.

"It’s a devastating picture that is emerging from what has happened in Nepal," Burnham says during a visit to South Wales.

"Immediate action" is being taken and the UK is deploying consular support staff to the region "so that British nationals will be able to access support 24/7", he adds. The latest from Nepali police is that 33 UK nationals are currently missing.

“Obviously, there are a number of British nationals who currently are thought to be missing and we’ll be providing all the support we can to their families in what is a very distressing and devastating situation," he adds.

Burnham says the UK has also offered to send emergency responders to the region, but "that’s obviously a matter for the Nepalese government".

Phanindra Dahal
BBC Nepali, reporting from Trishuli

The Nepal Army says it has rescued more than 350 people so far today from areas affected by the flooding.

The army’s spokesperson said 50 of those rescued were foreign nationals, including 30 Indians, eight Chinese, eight Koreans, two Americans and two Italians.

Anahita Sachdev
BBC News, Delhi

Sisters Ashna and Shreya Ahuja are desperately waiting for news of their parents after flash floods struck Nepal.

Deepak and Madhu Ahuja had travelled from Texas to Mount Kailash on a group pilgrimage organised by the spiritual group Isha Foundation to celebrate Deepak's 60th birthday.

The couple had completed the trip and were crossing from Tibet into Nepal when floods hit near the border, their daughters say.

One of the siblings spoke to their parents just hours before the floods.

The sisters have contacted the US State Department and US embassies in Delhi, Nepal and China, but they say they have no concrete information on the whereabouts of their parents.

“It’s only been one day, but it has felt like much longer,” the sisters tell the BBC. “We just love them a lot and want them to come home.”

Image source, Ahuja family

Phanindra Dahal
BBC Nepali, reporting from Trishuli

I am outside a military training centre in Trishuli and have already seen a few rescue helicopters moving in and out.

Dozens of people are outside the barracks to find out the whereabouts of their missing relatives.

It's a military training centre but the army has converted it into a forward rescue base with military and private helicopters co-ordinating search operations.

Image source, Getty Images

India’s foreign ministry says there are 288 Indian nationals who remain uncontactable following the floods in Nepal and Tibet.

Approximately 200 Indian nationals have been stranded in Tibet and are seeking to be evacuated following the floods, India’s foreign ministry spokesperson Randhir Jaiswal says in a press briefing.

“There may be some people who are missing there and we are trying our best to locate them through the local authorities,” he adds.

Jaiswal says 21 Indian nationals, who travelled to Nepal for the Kailash Mansarovar Yatra – a sacred pilgrimage to Mount Kailash - have been rescued.

Image source, Reuters

The director of the Centre for Disaster Studies at the Tribhuvan University in Nepal, Basanta Raj Adhikari, has told BBC Newsday there is a risk of "second and third waves" today or tomorrow.

"We don't know yet," he says, adding that he continues to discuss the situation with colleagues in China who are monitoring the situation. "There isn't high rainfall, but [a] landslide might happen."

He adds that they have been monitoring Himalayas mountain hazards - "climate change is really happening here," he explains.

"We are observing but we didn't know that that would happen on [a] particular day."

In its latest update on social media, Nepal police says 270 bodies have now been recovered from areas affected by Wednesday's floods.

About 100 Chinese nationals are reported to be missing following flash floods in Nepal, according to China's foreign ministry spokesperson Lin Jian.

Lin says China is maintaining close communication with Nepal and supporting joint search and rescue efforts. He adds that China would also provide emergency assistance based on Nepal's needs.

The number of people missing in the mudslide disaster in Tibet's Gyirong county has risen to 558, which includes 260 foreign nationals, according to China's state broadcaster CCTV.

A further 826 people are missing in Nepal, Nepal's National Disaster Risk Reduction and Management Authority said in its latest update. It's currently not clear if these figures overlap with China's.

Image source, Reuters

A tour guide who made a last-minute decision to postpone his group's journey through Gyirong into Nepal has recounted their close shave with the flooding, describing Wednesday as "a day of immense luck, yet one weighed down by a heavy sense of foreboding".

“It rained all night [on Tuesday], and I was worried we wouldn’t be able to see the snow-capped mountains," the guide, surnamed Mu, has told Zhejiang-based Tide News. "So I decided to lead them up first to a viewpoint in another area."

While the group was trekking in this other spot on Wednesday morning, they heard a "loud rumbling sound".

"No one could have imagined it was a mudslide,” Mu says.

At midday, they descended and proceeded to apply for permits to enter Nepal through the Gyirong border crossing.

This process typically takes an hour, but on Wednesday, "our permits never came through", Mu notes.

"It's only then that we caught up with the news and realised what had happened."

Image source, EPA

David Fisher, head of the International Federation of the Red Cross and Red Crescent Societies delegation in Nepal, says there is "still an extreme situation" in the regions hit by Wednesday's floods.

He tells 5 Live Breakfast some areas in the north of Nepal "are only accessible via helicopter because the flood has knocked out bridges and roads".

"Our team has been on the ground a bit south of there and they have been able to travel to make contact with local volunteers."

Fisher says "it's very clear to us there are very sharp needs" and a lot of people had to "sleep in the elements" last night, but "much, much more is needed".

He adds that entire villages and market places have been "swept away" and fears the death toll "could continue to go up".

At least 77 of the people missing in Nepal were travelling with the Isha Foundation, founded by Indian spiritual leader Sadhguru.

The group had completed its pilgrimage to Kailash Mansarovar and was heading back to Kathmandu when contact was lost, according to the foundation's coordinator, Maa Gambhiri.

She told news agency ANI that one of the foundation's team members spoke to group leader Praveen at 09:05 local time (04:20 BST) on Wednesday. When they tried to contact him again 10 minutes later, they could not get through.

“We couldn't get through to him or anyone else. It seems the incident occurred within those 10 minutes.”

The foundation says it is still waiting for information from the authorities.

The group includes people from the US, Australia, the UK and several European and Asian countries. Many are of Indian origin, Gambhiri said.