BANGKOK (THOMSON REUTERS FOUNDATION) - Activists called for renewed scrutiny of hydropower projects in Laos after a dam that was under construction broke, killing at least 19 people as it swept away homes in flash flooding.

More than 3,000 people need to be rescued in a remote part of the country's south, where at least seven villages were submerged in muddy water on Monday (July 23).

As rescuers tried to reach people in Attapeu province, analysts and activists called for greater scrutiny and accountability of the many hydropower projects that are planned in one of the poorest countries in the world.

"Many of the people affected by the dam collapse had already been displaced or had suffered livelihood losses and other impacts due to the construction of the dam," said Maureen Harris at the advocacy group International Rivers.

"This tragedy has compounded their suffering, and highlights the safety risks, in addition to concerns about the social and environmental impacts," she said on Wednesday (July 25).

Calls to government offices in the capital, Vientiane, were not returned.

Officials in Laos are betting on an ambitious dam-building programme to generate desperately needed investment for the country, which aims to become the "battery of Asia".

The dam that collapsed is part of the hydroelectric Xe-Pian Xe-Namnoy power project.

More than 2,300 people were resettled to make way for its reservoir, with an additional 8,700 directly affected by the project, according to estimates by the developer in 2013.

More than a dozen dams are planned with foreign investors, including Thai, South Korean and Chinese firms, under terms that require Laos to export electricity to its more developed neighbours.

While benefits from the projects are primarily for non-locals, the environmental and social costs are borne by local communities, said Micah Ingalls at the University of Bern's Centre for Development and Environment in Vientiane.

Yet regulatory oversight, and the environmental and social monitoring of these projects is often inadequate, he said.

"Local government agencies and communities who see impacts on a day-to-day basis typically have low involvement," he told the Thomson Reuters Foundation.

Federal teams are often "under-funded and under-capacitated to carry out adequate monitoring, and so rely on the expertise and responsibility of the dam investors," he said.

Environment rights groups have repeatedly warned about the human and environmental cost of the rapid pace of dam construction, including damage to the already-fragile ecosystem of the region's rivers.

The United Nations working group on business and human rights has called on wealthier nations in the region to apply best practices to their overseas operations.

But while standards exist on paper, there is little oversight, and limited access to courts and other remedies when violations occur, said Harris.

"The pace at which these projects are being built is clearly not sustainable," she said.

"We hope this tragedy will force a pause on dam projects and trigger critical thinking on if - and how they must be done."