Volkswacht Bodensee - Hundreds missing after Nepal-Tibet flood kills more than 100

Aid workers said entire settlements had been "wiped out". Surveillance footage verified by AFP shows dozens of people running for their lives as a stories-tall surge of debris slammed into the Chinese side of a border area, tossing lorries and buses aside.

Chinese state media reported "major casualties" from a mudslide at a Tibet border hub, reporting three dead and another 265 people missing.

Nepali police said that "100 people have died due to the devastating floods", with officers "working to move families in flood-risk areas... to safer locations."

Rescuers waded through mud and sludge to look for survivors after floodwaters buried the lower floors of multi-storey buildings.

Some 403 tourists -- 341 of them foreigners -- were unaccounted for several hours after the disaster struck, according to the tourism ministry.

The missing foreigners included 142 Indians, as well as others from Australia, Britain, Malaysia, the Netherlands, Portugal, South Africa, South Korea and the United States, the tourism board said.

"Entire villages and market areas have been wiped out," said David Fisher, the Nepal head of the International Federation of Red Cross and Red Crescent Societies (IFRC).

It was dispatching emergency supplies including blankets, first aid kits, stretchers and body bags, it said.

Nepal's Prime Minister Balendra Shah vowed a maximum response.

"The pain and loss you have suffered is not small," he said in a statement on social media. "But I want to assure you that you are not alone in this difficult time -- the state is with you with all its means and resources."

- Risk of new flood? -

Locals were traumatised, while experts cautioned that a lingering blockage in a river could produce an additional flood.

"I got a call from (my brother-in-law) this morning, and they were crying and said their entire house had been swept away. Three family members were rescued, but his brother is still missing," said 56-year-old local Raju Bhadel.

The cause of the flooding was not immediately clear.

But Nepal's Foreign Minister Shishir Khanal said an earthquake likely triggered a landslide, which in turn blocked a river, sending water gushing downstream.

Nepal's disaster authority said that satellite data indicated that a "snow-rock landslide" on the Nepal-China border may have caused the flood.

Images shared by Nepali police showed floodwater surging through a river, sweeping away houses in its path, while AFP images depicted the top floor of a house sticking out from muddy soil.

The Nepali Army was carrying out flights and had rescued scores of people, while others living near the river in danger zones had been told to relocate.

The Nepal Electricity Authority said about 430 megawatts of production capacity, including from hydropower and solar facilities, had been damaged "resulting in disruption" of the supply.

- 'Mudslide disaster' -

Sarthak Shrestha, a remote sensing and geo information analyst at the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD), said a preliminary assessment showed "no anomalies" from China's side of the border.

"We believe a rock-ice avalanche occurred in Nepal, blocking the Lhende river and causing the cascading flood event," he told AFP.

Chinese state broadcaster CCTV reported on Wednesday that "a mudslide disaster" on the Nepali side resulted in "major casualties and missing people" at the Gyirong Port in Tibet.

China's leader Xi Jinping said that "the most urgent task is doing everything possible to search for and rescue the missing people", according to CCTV.

Monsoon rains from June to September regularly trigger deadly floods and landslides across South Asia.

Scientists say climate change is increasing the frequency and intensity of extreme weather events in the region.

Qianggong Zhang, head of climate and environmental risks at ICIMOD, warned of the potential for a second flood.

"With a blockage still lodged upstream on the Nepal-China border river, authorities warn a second flood may occur," he told AFP.

B.Baumann--VB