A flooded road following a flash flood in Galchhi in the Dhading district, Nepal, 26 August 2026. Picture taken with a mobile phone; Credit: REUTERS/Stringer

KATHMANDU (Reuters) - A massive flash flood in the Himalayan nation of Nepal washed away villages while damaging roads, bridges and power projects in a region bordering Tibet, authorities said on Wednesday 26 August 2026, as they warned against the risk of casualties.

The areas of Syapru Besi and Timure in the mountainous district of Rasuwa, with a population of about 50,000, were severely affected, officials said, while urging those living on the banks of the Bhote Koshi river to seek higher ground.

"We have reports of villages and infrastructure project sites being washed away," district administrator Narendra Pariyar told Reuters, although no immediate estimates of casualties or property losses were available.

"There could be heavy casualties or loss of property," he added. "But I cannot say for sure now."

The reason for the inundation was not immediately clear but a deadly flash flood on the same river last year was eventually traced to the draining of a glacier lake.

Nepal's water resources ministry said hydroelectric projects were among the infrastructure damaged by the floods, along with roads and bridges.

Electricity supply in the area has been disrupted as a result of such damage, the government added.

Prime Minister Balendra Shah said rescue and relief teams, as well as police and the military had been dispatched to help in the aid effort.

"Instructions have been given ... to move the people living in the lower areas to safer places," he said.

"People along the river are advised to exercise extra caution and remain alert."

The Bhote Koshi river originates in Tibet and empties into Nepal's Trishuli river that eventually flows into India as the Gandak river.

Last year's flood in the Bhote Koshi killed nine people, with 24 missing, and washed away a 'Friendship Bridge' linking Nepal and China to disrupt trade and transport for months.

That flood was triggered by the draining of a supraglacial lake in Tibet, a regional climate monitor said.