An environmental group says a Thai company is going ahead with work on a controversial hydroelectric dam on the Lower Mekong River, despite an agreement to postpone a final decision on the project.

U.S.-based International Rivers says it has discovered that preliminary construction has continued on the $3.5 billion Xayaburi Dam in Laos, including an access road in and out of the area.

The regional Mekong River Commission, which includes Thailand, Cambodia, Laos and Vietnam, agreed in December that further study was needed to assess the dam's environmental impact, though the decision is not legally binding.

Pianporn Deetes, International River's Thailand campaign coordinator, tells VOA the dam could have an uncertain environmental impact on the 60 million people who live along the Mekong River basin and depend on its fisheries for their livelihoods.

“The impact would not only be on the dam side, or in Thailand, but also go to Cambodia and delta, in Vietnam, the Mekong Delta, which is the rice bowl of Vietnam.”

Deetes says Thailand does not need the electricity the proposed Xayaburi Dam will produce.

Laos, one of the world's poorest nations, expects a huge economic benefit from selling most of the dam's 1,200 kilowatts of hydroelectric power into Thailand.