Environmental groups filed a federal lawsuit Wednesday against Chevron Phillips Chemical Company LLC alleging that its Cedar Bayou chemical plant near Houston has repeatedly violated the Clean Air Act.

The Sierra Club and Environment Texas claimed the Baytown, Texas, plant has released more than a million pounds of excess air pollutants since 2003.

The plant is the company's largest domestic manufacturing facility, where olefins and other chemicals are produced. Chevron Phillips is jointly owned by Chevron Corp. (CXV) and ConocoPhillips (COP).

The two sides plan to meet to discuss a settlement, said Philip Hilder, one of the attorneys representing the environmentalists. However, there is no guarantee that an agreement will be reached, Hilder said.

Chevron Phillips is committed to lowering pollution at the plant and has reduced the amount of emissions it has made since 2001, said company spokesman Brian Cain.

In April, the same environmental groups filed a similar lawsuit against a Houston-area refinery partly owned by Shell Oil Company, the U.S. subsidiary of Royal Dutch Shell (RDSA). Shell agreed to pay $5.8 million, which was distributed to local community groups.

-By Susan Daker, Dow Jones Newswires; 713-547-9208; susan.daker@dowjones.com