California legislators May 17 began investigating the tactics of oil companies, which have realized big profits as fuel prices rise to record levels, The Los Angeles Times reported.

The probe by the Senate Select Committee on Gasoline and Diesel Pricing will be modeled after an investigation by lawmakers into price manipulation during California's electricity crisis, the article said.

The Department of Energy said Monday the statewide average price of regular gasoline rose 4.6 cents last week to a new high of $2.269 a gallon.

California's average retail price for diesel fell 1.6 cents from last week's record high to $2.34 a gallon.

State Sen. Joe Dunn, D-Santa Ana, intends to show that oil companies have deliberately contributed to California's precarious supply-and-demand situation, The San Jose Mercury News reported.

"Is there a supply problem? Yes. But there's a supply problem as a result of a deliberate strategy of the gasoline industry," Dunn told the paper. "They have purposely eliminated their excess inventories, they claim in an effort to save costs, but conveniently, it also gives rise to market power and their ability to dictate the prices at will."

Shell Oil Co. plans to close its Bakersfield, CA, refinery this year. The facility makes 2 percent of California's gasoline and 6 percent of its diesel.

The company has said the closure is necessary because of declining crude supplies. But Dunn, U.S. Democratic Sen. Barbara Boxer and others have said they suspect Shell of intentionally crimping supplies.

At Boxer's request, the Federal Trade Commission is reviewing Shell's decision. The state attorney general has also questioned Shell's move, and legislative committees have held hearings to discuss rising fuel prices in California.