An U.S. environmental group is denouncing a report commissioned by Laos that recommends going ahead with a proposed hydroelectric dam on the Mekong River.

The group, International Rivers, says the study by a Swiss-based company (Poyry Energy AG) represents “a desperate bid” by Laos to gain approval for the multi-million dollar Xayaburi Dam from neighboring Thailand, Vietnam and Cambodia.

The three countries and Laos make up the Mekong River Commission, which has laid out numerous requirements for the dam. But International Rivers says the Swiss report fails to address more than a dozen of those requirements, including one that provides for the safe migration of important fish species found in the river.

Ame Trandem, a regional program director for International Rivers, says the report “sidesteps science and relies instead on guesswork.”

Laos agreed in April to a request from its fellow MRC members to conduct an additional study on the impact of the proposed dam.

It expects a huge economic benefit from selling most of the dam's 1,260-kilowatts of hydroelectric power to Thailand. But Vietnam and Cambodia, along with environmental groups, fear the project will disrupt fish migration patterns, affecting the 60 million people who depend on the river for their livelihoods.

The MRC is expected to make a final decision whether to approve the dam at a meeting in Cambodia early next month. However, Laos could go ahead with the project even without the group's approval.