Several people have been killed and hundreds are missing after a hydroelectric dam collapsed in southeastern Laos, releasing five billion cubic metres of water.

The Xepian-Xe Nam Noy hydropower dam in Attapeu province collapsed on Monday evening, releasing large amounts of water and sweeping away houses, according to state media.

The official news agency KPL said more than 6,600 people have been left homeless.

Laos dam collapse: broken hydroelectric power plant floods villages Show all 15 1 /15 Laos dam collapse: broken hydroelectric power plant floods villages Laos dam collapse: broken hydroelectric power plant floods villages Lao villagers stranded on rooftops of houses after they had to evacuate them due to floodwaters after the Xe Pian Xe Nam Noy dam collapsed, in a village near Attapeu province in Laos EPA/ABC Laos News Laos dam collapse: broken hydroelectric power plant floods villages Hundreds of people were reported missing while several others were killed after the hydroelectric dam burst, causing heavy flash floods through several villages AFP/Getty Images Laos dam collapse: broken hydroelectric power plant floods villages Lao villagers evacuate on a boat EPA Laos dam collapse: broken hydroelectric power plant floods villages Villagers carry their belonging as they evacuate REUTERS Laos dam collapse: broken hydroelectric power plant floods villages Thousands of people have been left homeless and hundreds of households are submerged underwater AP Laos dam collapse: broken hydroelectric power plant floods villages Villagers inside a temporary shelter REUTERS Laos dam collapse: broken hydroelectric power plant floods villages People sitting on a rooftop of a house surrounded by floodwaters AFP/Getty Images Laos dam collapse: broken hydroelectric power plant floods villages Lao military preparing for rescue efforts Getty/ABC Laos News Laos dam collapse: broken hydroelectric power plant floods villages Villagers take refuge on a rooftop above flood waters AP Laos dam collapse: broken hydroelectric power plant floods villages Villagers inside a temporary shelter REUTERS Laos dam collapse: broken hydroelectric power plant floods villages An aerial view of the flooded plains in Attapeu province AFP/Getty Images Laos dam collapse: broken hydroelectric power plant floods villages Dogs take refuge on a rooftop AP Laos dam collapse: broken hydroelectric power plant floods villages Structures surrounded by floodwaters AFP/Getty Images Laos dam collapse: broken hydroelectric power plant floods villages Villagers inside a temporary shelter REUTERS Laos dam collapse: broken hydroelectric power plant floods villages A villager takes refuge on a rooftop above flood waters AP

Officials have called in boats to help evacuate people in the San Sai district as water levels rise following the collapse of the dam, ABC Laos news reported.

A video posted by the news network on its Facebook page taken from a helicopter flying over the flooded region showed the roofs of submerged houses visible above the muddy water.

Provincial authorities issued a call for emergency aid – clothing, food, drinking water, medicine, cash and other items – from the “party, government organisations, business community, officials, police and military forces and people of all strata”.

Villagers were stranded on roofs after evacuating their homes after the Xepian-Xe Nam Noy dam collapsed in a village near Attapeu province (EPA/ABC Laos news)

The dam was constructed by a joint venture led by South Korean companies, with Thai and Lao partners.

The project, scheduled to begin operating this year, was still under construction, KPL reported.

It described the portion which collapsed as a “saddle dam”, an auxiliary dam used to hold water beyond what is held by the main dam.

The company building the dam said heavy rain and flooding caused the collapse and it was cooperating with the Laos government to help rescue villagers near the dam.

Lao villagers stranded on a roof of a house after they evacuated floodwaters (EPA/ABC Laos news)

“We are running an emergency team and planning to help evacuate and rescue residents in villages near the dam,” an SK Engineering and Construction spokesman told Reuters.

The prime minister of Laos, Thongloun Sisoulith, “suspended the planned monthly meeting of the government for August and led his cabinet members and other senior officials to Sanamxay [district] to monitor rescue and relief efforts being made for flood victims,” KPL said.

Many areas of Laos have recently been hit by flooding from seasonal rains.

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Communist Laos, one of Asia’s poorest and most secretive countries, aims to become the “battery of Asia” by selling power to its neighbours through a series of hydropower dams.

For years, environmental rights groups have raised concerns about the southeast Asian nation’s hydropower ambitions, including worries over the impact of dams on the Mekong River, its flora and fauna and the rural communities and local economies which depend on it.