The Associated Press

LITTLE ROCK, Ark. (AP) - Two environmental groups asked state regulators Wednesday to deny a permit for the construction of a coal-fired power plant in southwest Arkansas, saying it would violate the federal Clean Air Act.

In a six-page brief, the Sierra Club and National Audubon Society asked the Arkansas Pollution Control and Ecology Commission to examine the issue at its next meeting. The two groups warn the permit for the $1.6 billion coal-fired plant in Hempstead County, wanted by Southwestern Electric Power Co., didn't take into account the impact of small particles that would be released by plant.

The groups wrote that regulators at the Environmental Protection Agency recently overturned a permit for a similar coal-fired plant in Kentucky on those grounds.

"The permit approved (by the state) does not satisfy the requirements of the Clean Air Act," the groups wrote. "If the commission fails to follow the federal law then EPA will veto the commission's permit decision."

Peter Main, a SWEPCO spokesman, said the company's permit for the plant was already one of the most stringent in the nation. Main said the company would file a response in the coming days.

In June, the Arkansas Court of Appeals overturned a permit by the Public Service Commission for the plant. SWEPCO filed a request with the state Supreme Court to review the ruling.

SWEPCO is a subsidiary of Columbus, Ohio-based American Electric Power, among the largest electric utilities in the country. SWEPCO has 111,000 customers in Arkansas and 340,000 more in Louisiana and Texas. Regulators in those states had already approved the plant, which would affect ratepayers there. The company filed papers with the Arkansas Public Service Commission in January 2006.