WASHINGTON (AP) – Federal investigators said Wednesday that traders at BP PLC cornered the U.S. propane market in the winter of 2004 to manipulate prices, driving heating costs higher for rural consumers.

In a lawsuit filed against the company’s BP Products North America Inc. unit, the Commodity Futures Trading Commission said that BP traders – with the consent of senior management – “purchased enormous quantities of propane to establish a dominant” position in the market. They then withheld fuel from the market to drive prices higher, with the intent of reaping as much as $20 million in profits.

The civil lawsuit was filed in the U.S. District Court for the Northern District of Illinois.

Separately, the Department of Justice announced Wednesday that a former BP trader, 34-year-old Dennis N. Abbott of Houston, has pleaded guilty “to conspiring to manipulate and corner the propane market.”

BP intends to fight the charges in court.

The agency said Abbott, who has agreed to cooperate with law enforcement in “an ongoing investigation,” faces up to five years in prison and a fine of $250,000.

BP spokesman Ronnie Chappell said “market manipulation did not occur.” However, Chappell said an internal investigation conducted by BP found that several employees failed “to adhere to BP policies governing trading activities” that they were dismissed from the company.

“We have also taken steps to strengthen the supervision of our trading activities,” Chappell said.