• Scale of disaster in remote southern tip of Laos remains unclear
• Lao News Agency says 27 people dead, more than 130 missing
• Heavy rains caused dam to wash away - South Korean company
• Villagers in neighbouring Cambodia moved to higher ground

KHOKONG: Troops searched for survivors in the remote southern tip of Laos on Thursday, three days after the collapse of a hydropower dam sent a torrent of water charging across paddy fields and through villages, as rescuers rushed aid to thousands of homeless.

The scale of the disaster was still unclear, in part because of the inaccessibility of the area but also because reports from the communist country's state media have been scant and sketchy.

The official Laos News Agency said that 27 people were confirmed dead and 131 were missing following the failure of the dam on Monday, a subsidiary structure under construction as part of a hydroelectric project in the province of Attapeu.

Earlier reports had suggested the death toll would be much higher, and on Wednesday the Vientiane Times had said more than 3,000 people were waiting to be rescued from swirling floodwaters, many of them on trees and the rooftops of submerged houses.

In the village of Khokong, a sea of mud oozed around the stilt houses that were still standing and dead animals floated in the water.

"Seven villages were hit, two very badly. There were 200 houses and only about 10 are left standing," said a medical official, who declined to be named because he was not authorised to speak to the media.

"We retrieved one body today. I suspect there will be more as the water goes down and the road becomes easier to access."

He said villagers were warned about three to four hours before the dam burst, but few had expected the water to rise as high as it did.

The UN Office for the Coordination of Humanitarian Affairs said roads and bridges were damaged, and boat and helicopter were the only means of transport in the worst-affected areas.

Schools in safe areas were being used as evacuation centres, and about 1,300 families needed tents for shelter, it said.

On a road to the small town of Sanamxai, Reuters saw trucks carrying aid, including fresh water and blankets, for those made homeless. The government put their number at 3,060.

Phra Ajan Thanakorn, a Buddhist monk returning from Sanamxai, said he had delivered food and medicine in four pick-up trucks that had come from Vientiane, the capital some 800 km (500 miles) to the north, and he was heading back there to load up with more.

"The situation is really bad," he told Reuters. "All the relief efforts are at Sanamxai. There are volunteers distributing food and medicine for survivors every day there. They are still lacking food, medicine, and coffins."

Rescue and relief teams from around Asia have headed into Attapeu, a largely agricultural province that borders Vietnam to the east and Cambodia to the south.

"BATTERY OF ASIA" AMBITIONS

Laos, one of Asia's poorest countries, has ambitions to become the "battery of Asia" through the construction of multiple dams.

Its government depends almost entirely on outside developers to build the dams under commercial concessions that involve the export of electricity to more developed neighbours, including power-hungry Thailand.

Laos has finished building 11 dams, says Thai non-government group TERRA, with 11 more under construction and dozens planned.

Rights groups have repeatedly warned against the human and environmental cost of the dam drive, including damage to the already fragile ecosystem of the region's rivers.

The dam that collapsed was part of the $1.2 billion Xe-Pian Xe-Namnoy power project, which involves Laotian, Thai and South Korean firms. Known as "Saddle Dam D", it was part of a network of two main dams and five subsidiary dams.

The project's main partner, South Korea's SK Engineering & Construction, said part of a small supply dam was washed away and the company was cooperating with the Laos government to help rescue villagers.

The firm blamed the collapse on heavy rain. Laos and its neighbours are in the middle of the monsoon season that brings tropical storms and heavy downpours.

In Cambodia's northern Strung Treng province, nearly 1,300 families that were also affected by the flooding from the dam in Laos were moved to higher ground.

"These people will be affected for about seven to 10 days and once all the water flows into the Mekong, we will be fine," said Keo Vy, a spokesman for the National Centre for Disaster Management.

An official at SK Engineering & Construction said fractures were discovered on the dam on Sunday and the company ordered the evacuation of 12 villages as soon as the danger became clear.

Laotian Minister of Energy and Mines Khammany Inthirath told a news conference in the capital that the company could not deny responsibility for the destruction of livelihoods and property. The Vientiane Times cited him as saying that all compensation would be "borne by the project developer 100 percent".