Taking action where the Bush administration would not, four northeastern states said yesterday that they will sue five West Virginia power plants for violating the Clean Air Act's pollution-control rules.

The lawsuit -- which will be filed 60 days from now unless the four attorneys general reach an agreement with Allegheny Energy Inc. -- marks the latest skirmish in a long-running battle over the Environmental Protection Agency's handling of New Source Review, the federal requirement that coal-fired power plants built before 1970 install new pollution controls when they upgrade their facilities.

The EPA had spent years investigating possible violations of the requirement but announced in November that it would not bring any new lawsuits unless a plant violated the administration's less stringent interpretation of the law.

The states taking the action are New York, Connecticut, New Jersey and Pennsylvania, where Allegheny Energy has headquarters.

"These cases reflect our continued intent to enforce the Clean Air Act even when the EPA has dropped the ball," New York Attorney General Eliot L. Spitzer said in an interview.

When the EPA stopped its investigation of about 50 cases, Spitzer requested copies of several agency files, including one involving Allegheny Energy. The EPA turned over five to 10 files.

The letter issued yesterday asserts that emissions of sulfur dioxide and nitrogen oxide from the coal-fired plants cause smog, acid rain and respiratory disease in the four states.

Allegheny Energy spokesman Mike Grandillo said the company is reviewing the complaint.

EPA spokeswoman Cynthia Bergman declined to comment on the planned lawsuit but said, "The most important thing we can do to improve air quality in this country is to reduce pollution from power plants, and we have proposed the clean-air interstate rule that will require power plants to reduce their emissions by 70 percent."

The administration's revised New Source Review regulation is tied up in litigation, and in the meantime the administration has pledged to enforce the existing rule.

Angela Ledford, director of the environmental group Clear the Air, said it was significant that Pennsylvania's attorney general was willing to sue a home-state company and that states were pushing for enforcement.

But Scott Segal, who heads the Electric Reliability Coordinating Council, an industry group, called the lawsuit misguided. "Emissions from power plants have been declining for decades," he said. "More litigation does nothing to improve the environment."