At least 19 people have died and dozens are missing in Laos after a hydropower dam under construction collapsed.

Laos News Agency reports that the accident in the southeastern province of Attapeu has released five billion cubic metres of water, enough to fill more than two million Olympic swimming pools.

Boats have been brought in to help evacuate people as water levels rise, according to ABC Laos news, with reports the flash flooding has left more than 6,000 people homeless in six villages in the southeast Asian country.

A video posted on the network's Facebook page shows villagers watching the fast-flowing water from the side of a river bank.

Image: The Red Cross said the disaster has 'caught everyone unawares'

The portion of the dam that collapsed on Monday is reported to be a "saddle dam", an auxiliary structure used to hold water beyond what is held by the main dam.


A spokesman for the one of the companies involved in the project said heavy rain and flooding caused the collapse. He said the firm was co-operating with the government to rescue villagers.

"We do not have any formal information yet about any casualties or how many are missing," an Attapeu official told the AFP news agency on condition of anonymity, adding that there was no phone signal in the region.

"We sent rescue teams who will help them and provide basic assistance first," the official added.

Image: Villagers carry their belongings as they evacuate in the wake of the collapse

The Red Cross has staff and volunteers on the ground helping with the response to the disaster, with the organisation saying it has "caught everyone unawares".

The $1.2bn (£915m) dam is part of a project by Xe-Pian-Xe Namnoy Power Company, a joint venture which is also known as PNPC.

A number of companies are involved, including Thailand's Ratchaburi Electricity Generating Holding, South Korea's Korea Western Power and the state-run Lao Holding State Enterprise.

South Korea said 53 of its nationals were taking part in the construction and were evacuated in advance of the collapse.

The 410 megawatt capacity dam, close to the border with Cambodia, was meant to begin commercial operations by 2019.

Image: A computer-generated image of a dam being built in Laos by Xe-Pian Xe-Namnoy Power Company

It was to form part of a series of dams over the Houay Makchanh, the Xe-Namnoy and the Xe-Pian rivers in neighbouring Champasack province.

The plan was to export 90% of the electricity generated to Thailand, with the rest offered up on the local grid.

Environmental groups have long voiced fears about hydropower ambitions in impoverished and landlocked Laos, with around 10 dams in operation, another 10 to 20 under construction and dozens more in the planning stages.

In particular, concerns have been raised about the impact on the Mekong River, its flora and fauna and the communities that depend on it for their livelihoods.

As well as disquiet within Laos, several neighbouring nations are worried its ambition to become the "battery of southeast Asia" will disrupt vital ecosystems and their own river systems.