Federal investigators are examining whether BP Plc manipulated crude oil and unleaded gasoline markets, according to a report in The Wall Street Journal on Tuesday that cited lawyers and traders close to the case.

BP confirmed the investigations, but declined further comment. We are aware of the investigations, but we are not going to comment on the specifics, a BP spokesman in London said.

The Journal said the federal investigations signal a rise in regulatory scrutiny of the major oil company.

The newspaper said BP, which has been summoned before Congress next week over problems at its Alaska pipelines, already faces a civil complaint filed by federal commodities regulators for allegedly manipulating much of the U.S. market for propane.

The separate investigations on crude oil and gasoline could intensify pressure on BP because these markets are bigger and directly affect most American households, The Journal reported.

At 0800 GMT, BP shares were down 0.5 percent at 602-1/2 pence, valuing the company at about 119 billion pounds ($225.8 billion).

The Journal said the crude oil probe was focused on possible manipulation of the global over-the-counter market in 2003 and 2004 and that the U.S. Commodity Futures Trading Commission had sent subpoenas to BP and energy traders.

The gasoline inquiry has been underway for more than a year and includes a criminal probe by the U.S. Justice Department, the newspaper said. It is examining a single day's trading on the New York Mercantile Exchange in 2002, The Journal said.

(Additional reporting by Mark Potter in London)