Eighteen dead and hundreds unaccounted for as flash flood hits Nepal-Tibet border

At least 18 people have been killed and nearly 400 others are unaccounted for after a flash flood and mudslide along the Nepal-Tibet border washed away villages and damaged roads and infrastructure.

The flood hit early on Wednesday in Rasuwa, just north of Nepal's capital Kathmandu, with preliminary information suggesting it was caused by an earthquake triggering an avalanche with melted snow pouring into the Bhote Koshi river.

Search operations are under way on both sides of the border and 88 people have been rescued so far, according to the Nepalese army.

State media in China, which controls Tibet, say there are significant casualties and Nepalese officials said they anticipate "huge scale loss".

The Nepal tourism board said work was under way to establish the whereabouts of 291 tourists and 93 Nepalese nationals, including guides, who were known to be in the area where the flood hit.

They include 12 travellers from the UK as well as Americans, Malaysians, South Africans and Indians.

Several areas downstream of the Bhote Koshi river, which flows from Tibet to Nepal, are on high alert and roads, communications and power in the region have been disrupted. The authorities say the main road to Kathmandu is closed.

Verified videos from Nepal show a bridge being swept away and multi-storey buildings collapsed by the force of floodwaters, as well as a town with many buildings destroyed.

BBC Verify has located the clips to the town of Trishuli Bazaar area of Nuwakot District in Bagmati Province, about 25km (16 miles) to the north-west of Kathmandu.

The video shows the river Trishuli suddenly becoming swollen by enormous amounts of water, which appears to have significantly increased in volume and speed and filled with sediment.

About 40 seconds into the clip, the weight of the flash flood rips the bridge off of its supports and carries it swiftly downriver. A few seconds later, several buildings also collapse.

The second verified video, filmed from the same location, shows the devastating aftermath. The river's level has risen significantly, trees and many buildings visible in the earlier video have been ripped away.

It is not clear exactly how many have been destroyed, but many buildings near the riverbank have disappeared, partially collapsed or are caked in sediment from the flood's force.

Yee Liang, a Chinese businessman based in Kathmandu, told the BBC his logistics company had seven container trucks based in the area, staffed by Nepalese employees.

"We have lost contact with all of them. There is no signal, so we cannot reach anyone," he said.

"As far as I know, there was no warning. There were occasional mudslides and landslides, especially in the rainy season, but this one seems much more serious."

Nepal Army Spokesman Rajarm Basnet told the BBC efforts were under way to rescue 115 people from the village of Mailung.

The Nepalese Ministry of Home Affairs warned there was likely to be huge loss of life in Timure, Syabrubesi and Betrawati. Flooding had also caused damage to the Trishuli hydropwer project.

The extent of the damage on the Tibetan side is unclear but the BBC spoke to Guan Daoxuan in Sichuan province who said he had lost contact with his wife late on Wednesday morning.

She works for a state-run construction company involved in building roads and bridges in Tibet. Guan said Nepalese authorities had tried to send a helicopter to inspect the area because road access had been cut off, but strong winds were making it difficult for the aircraft to reach the site.

Nepal's disaster management authority called on people living near river banks in vulnerable areas to remain alert and take precautions.

"Work has started to take necessary steps in co-ordination with the medical team, scouts, and Red Cross," Prime Minister Balendra Shah said in a social media post, after holding an emergency meeting to take stock of the situation.

Nepal's Foreign Affairs minister Shishir Khanal told parliament that 26 police personnel, nine armed police officers and 44 members of the military were missing.

He said an earthquake at 08:37 local time had triggered an avalanche and there was preliminary information that this had resulted in the flash flood.

Rasuwa saw deadly flooding last year that killed 18 people after a glacier burst on the Chinese side of the border.

Officials have told the BBC that they believe the scale of Wednesday's disaster exceeds last year's floods.