US concern at Laos building 1st dam across Mekong

WASHINGTON (AP) - The United States has criticised Laos' decision to build the first dam across the mainstream of the Mekong River which environmentalists warn could affect tens of millions of livelihoods and trigger a dam-building spree along South-east Asia's mightiest waterway.

The US has urged a moratorium on such projects until studies into their impacts are completed. But the State Department said on Monday that Laos has announced its intention to start construction on the US$3.5 billion (S$4.3 billion) Xayaburi dam despite lingering concerns downstream.

"The extent and severity of impacts from the Xayaburi dam on an ecosystem that provides food security and livelihoods for millions are still unknown," a department statement said.

Laos is one of Asia's poorest nations and hydropower is already a key source of revenue. The project, which will generate electricity for sale to neighboring Thailand, is strongly opposed by its longtime Lao ally, Vietnam.