Nepali authorities urged villagers on Sunday to move to safer ground after a flash flood swept away several houses.

A dry landslide in Chumnubri village in Gorkha district, about 100km west of Kathmandu, blocked the Budhi Gandaki River, leading to downstream flooding, authorities said.

Two women and three men were out of contact, the national disaster authority said, but there were no immediate reports of casualties.

Videos on social media show houses and sheds being swept away by the swollen river flowing between mountains.

The Budhi Gandaki River merges into the Trishuli River, where a glacier collapse caused a catastrophic flood in August that killed 1,457 people, with thousands still missing.

"We have asked villagers living along the river banks downstream to evacuate and remain safe," said Dharmendra Kumar Mishra, Gorkha district's most senior bureaucrat.

Mr Mishra said about a dozen houses and two suspension bridges had been swept away, and a hydro-electric project camp was damaged by the flood.

Residents rescued

The flooded river is rising and has washed away a highway bridge connecting two districts, the National Disaster Risk Reduction and Management Authority said.

The army said 49 people, including a foreigner, had been rescued. They did not give the person's nationality.

Another 18 workers at the hydro-electric project, whose camp was damaged, escaped to safety, said Dharam Raj Uprety, chief of the National Disaster Risk Reduction and Management Authority.

National disaster authorities alerted people living along the river in the Gorkha, Tanahun, Chitwan, East Nawalparasi and West Nawalparasi districts about the flood.

"Please help ensure that people in at-risk areas are moved to safe locations in time and assist search and rescue operations as needed," the National Disaster Risk Reduction and Management Authority said in a social media post.

Officials said army and police rescue personnel had reached the area and were also monitoring the situation from a helicopter.

Reuters/AP