Hundreds of people are missing and an unknown number are dead after a dam under construction collapsed in south-east Laos, state media say.

The collapse at the hydroelectric dam in Attapeu province late on Monday sent flash floods through six villages, Lao News Agency reported.

More than 6,600 people have been made homeless, it added.

Pictures showed villagers stranded on the roofs of submerged house and boats carrying people to safety.

"The disaster has claimed several human lives [and] left hundreds of people missing," the agency reported.

Attapeu is Lao's southernmost province, and borders Cambodia and Vietnam.

It is known for agriculture, rich trees and wood-based industries - and hydropower is one of its major exports. (BBC)