Environmental groups in the Mekong region have urged leaders of the Mekong riparian countries to use the Asean summit platform to demand the suspension of work on the Xayaburi dam.

The construction of the Xayaburi dam in Laos is proceeding despite the concerns of the Mekong River Commission (MRC) member countries, Save the Mekong coalition said in an open letter released yesterday, when the Asean summit started in Phnom Penh.

"The decision by Laos and Thailand to proceed with the dam not only threatens the livelihoods of riparian communities who depend on the Mekong but also undermines the integrity of the 1995 Mekong Agreement," the group said.

Laos has decided to resume work on the 107.6-billion-baht dam, despite fears it will have a devastating impact on food production downstream.

Thai Foreign Minister Surapong Tovichakchaikul backed the construction of the dam earlier this month.

The dam will be built by Thailand's construction giant Ch Karnchang, and the Electricity Generating Authority of Thailand will buy 95% of the electricity produced from the dam over a 28-year contract.

The group cited the MRC's technical review of the project, which warned that the dam could affect 23 to 100 fish species, and potentially lead to the extinction of the iconic Mekong giant catfish.

"There has never been a more urgent time for the MRC to uphold its responsibilities and speak out against the Xayaburi dam," the group said.

"Before it's too late, the MRC member countries must use the 21st Asean summit to demand the suspension of the Xayaburi dam and uphold their commitments to protect the Mekong River and its people."