KATHMANDU, Nepal -- Thousands of people have fled villages and towns along a mountain river in in northwest Nepal after it was blocked by a landslide that could burst and cause flash floods.

Government administrator Yam Bahadur Chokhal says the landslide blocked the Kaligandaki River early Sunday and the buildup of water has created a lake 2 kilometres (1.2 miles) long.

He says residents living on the banks of the river have been moved to higher grounds for fear that flash floods could sweep the area north of Beni Bazaar, about 200 kilometres (125 miles) northwest of the capital, Kathmandu.

Two powerful earthquakes devastated Nepal on April 25 and May 12, killing nearly 8,700 people and injuring 16,800 others. The quakes and aftershocks also have triggered many landslides in the Himalayan nation.