Vientiane, July 25 (IANS): Rescuers are searching for survivors after an under-construction hydroelectric dam collapsed in Laos on Tuesday, leaving at least 19 people dead and over 3,000 still to be rescued, media reports said on Wednesday.

At least seven villages in the southern province of Attapeu were completely flooded after the collapse at the Xe-Pian Xe-Namnoy hydropower project on Monday evening.

Sanamxay district Governor Bounhome Phommasane said that nearly 3,000 had been rescued and more than 3,000 were still in need of rescue, with more people stuck on trees and roofs of buildings, Efe reported.

He said seven villages and dwellings that are home to over 6,000 people were under water and nearly half the affected people are yet to be rescued or accounted for.

South Korea announced it would send an emergency relief team to Laos.

"President Moon (Jae-in) instructed the government to come up with strong support measures, including the dispatch of an emergency relief team, to Laos," the Presidential office said in a statement.

South Korea's Korea Western Power (KOWEPO) and SK Engineering and Construction (SK E&C) were part of the consortium that had built the Xe-Pian Xe-Namnoy hydropower project in southern Laos, one of whose auxiliary dam collapsed on Tuesday flooding entire villages.

The chairman of SK E&C, Ahn Jae-hyun, and several top executives of the company, who have set up a crisis cabinet, are already in Laos to monitor the emergency operation, the company said at a press conference on Tuesday.

There were conflicting numbers of people missing in the remote area reported in the state media outlets of the secretive Communist one-party state.

The Lao weather service has forecast strong to moderate rainfall in the coming days accompanied by strong winds in the region, which could further aggravate the situation.

Laos Prime Minister Thongloun Sisoulith traveled to the area to oversee the rescue and victim assistance operations.

Thai company Ratchaburi Electricity Generating Holding (RATCH), which is part of the construction project, attributed the collapse to the continuous rainfall that led a large volume of water to enter the reservoir.

The collapsed dam is part of a national plan to make use of the Mekong River flowing through the country and make Laos a source of electricity for Southeast Asia.

The joint venture Xe-Pian Xe-Namnoy Power Company won the $1.02 billion tender to build three 410 MW hydroelectric powerplants where the accident occurred.

The plan was for the plant to contribute to the national electric grid with an annual output of 1,860 GWh, upon its completion in 2019, according to RATCH.