Updated at 4pm

Hundreds of people are missing and several are feared dead after a hydropower dam under construction in southern Laos collapsed, causing flash flooding that swept away homes, state media reported on Tuesday.

The disaster left more than 6,600 people homeless, the Lao News Agency reported. It showed pictures of villagers wading through muddy floodwater carrying belongings. Others boarded rickety wooden boats or stood on the roofs of partially submerged houses.

Officials have brought boats to help evacuate people in San Sai district of Attapeu province in the southeast of the country as water levels rise after the dam collapsed, ABC Laos news reported.

A video posted by the news network on its Facebook page showed villagers stopping to watch fast-flowing water from the side of a river bank.

Environmental rights groups have for years raised concerns about Laos' hydropower ambitions, including worries over the impact of dams on the Mekong River, its flora and fauna and the rural communities and local economies that depend on it.

The South Korean 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.

"We are running an emergency team and planning to help evacuate and rescue residents in villages near the dam," a SK Engineering & Construction spokesman told Reuters by telephone.

Another official of SK Engineering & Construction said the company ordered the evacuation of 12 villages as soon as it became clear that the dam would collapse.

The South Korean foreign ministry said in a text message to reporters that 50 workers of the company and three from Korea Western Power Co. who were stationed at the construction site had been evacuated.

The dam collapsed at 8pm local time on Monday, releasing 5 billion cubic metres of water.

The prime minister of the Communist-run Southeast Asian nation, Thongloun Sisoulith, has suspended government meetings and led Cabinet members to monitor rescue and relief efforts in one of the affected areas, the state agency reported.

HYDROPOWER AMBITIONS A WORRY

One of Asia's poorest and most secretive countries, Laos is landlocked, but aims to become the "battery of Asia" by selling power to neighbours through a series of hydropower dams.

The collapsed dam was expected to start commercial operations by 2019 and export 90 per cent of its power to Thailand. The remaining 10 percent of power would be sold to the local grid under an agreement between the PNPC and the Electricite du Laos.

Photo: AFP

Photo: AFP

Photo: AFP

Photo: AFP

Photo: AFP

Photo: AFP

Video: AFP

Video: AFP

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