They claim the agencies illegally allowed EGAT to sign a contract to buy power from the controversial dam without transparency, the chairperson of the conservation network, Niwat Roikaew, said.
These Thai state agencies failed to inform the public in Thailand of environmental and social impacts from the dam, he said.
The 2007 Constitution requires concerned agencies to open a public hearing on any controversial project that may pose serious implications for the environment, society and public health, he said.
The Nation