Although crude oil prices spiked, and nervous motorists formed lines at gas stations in the hours after the terrorist attacks, world crude oil prices stabilized somewhat Wednesday on reassurances from OPEC that supplies would continue to flow normally.

On Tuesday, the price of a barrel of crude oil jumped $1.61, or 6 percent, then dropped 23 cents Wednesday to $28.83 a barrel on the London's International Petroleum Exchange, where oil continued to be traded. The New York Mercantile Exchange remained closed Wednesday.

"There is no shortage in supplies and there won't be," said United Arab Emirates Oil Minister Obaid bin Saif Al-Nasseri.

Market jitters remained, however, and analysts said any hint of U.S. retaliation in oil-producing regions likely would send prices soaring again.

The commodities market wasn't alone in its nervousness. On Tuesday, panicky motorists in parts of the U.S., including Illinois, lined up at some gasoline stations, creating traffic jams.

"It was panic-buying," said Mohamad Khan, manager of the Speedway station at Bode and Barrington Roads in Streamwood. "There was no reason for it."

According to station managers, customers coming home from work on Tuesday said they heard radio reports of $4-a-gallon prices in Missouri and Indiana and fearfully stopped to fill up their tanks. Many other motorists simply saw the long lines forming at the pumps and jumped in.

On Wednesday, acting on multiple complaints alleging gouging at some service stations, officials in several states warned service station managers against such practices.

Illinois Atty. Gen. Jim Ryan went so far as to file suit in Sangamon County against one Iowa-based service station chain, Casey's General Store Inc., alleging consumer fraud.

The suit asserts that Casey's was trying to "seize on the public misperception that there will be an abnormal market disruption of an essential commodity in the recovery period following a terrorist attack."

Casey's posted a response on its Web site, saying, "We acknowledge that a limited number of stores, primarily in Illinois, followed the market up in the pricing of gasoline. As soon as we learned of the situation, we took corrective action."

In the Chicago area, some gas stations raised prices overnight. In at least one case, the price for a gallon of regular unleaded jumped to $2.15 from $2 in the 24-hour period. Still, a check of about a dozen northwest suburban locations found prices ranging from $1.79 for a gallon of regular unleaded to $2.08 for premium.

Meanwhile, Illinois State police are monitoring gasoline prices statewide for possible gouging, said Mike Chamness, director of the Illinois Emergency Management Agency.

In downstate Shelbyville, Mayor Bill Shoaff and Police Chief Brent Fogleman ordered the city's four gasoline stations closed for three hours Tuesday after blockslong lines streamed onto city streets.

Customers filling numerous gasoline cans tested the patience of those behind them in line. "It didn't come to fisticuffs, but it was pretty close," Shoaff said.

Several major oil companies, including Exxon Mobil Corp., Citgo Petroleum Corp. and BP PLC, said they didn't raise prices. "Our prices didn't increase today or yesterday," said Patrick McGinn, a spokesman for Exxon Mobil.

But Bill Fleischli, executive vice president of the Illinois Petroleum Marketers Association, which represents independent service station owners, asserted that prices on the wholesale market for gasoline did indeed rise shortly after the attacks Tuesday, thus raising the cost of gasoline for dealers.

On Tuesday morning, Fleischli said, wholesale prices were around $1.10 and had reached $1.30 or $1.40 by 6 p.m.

Bill O'Grady, vice president for futures research for A.G. Edwards & Sons in St. Louis, said, "Gasoline inventories are more than adequate, if people just don't panic."

Both the U.S. Department of Energy and the state have established consumer hotlines to report alleged gouging. They are 800-244-3301 for the DOE, 800-386-5438 for the Illinois attorney general's office in Chicago and 800-243-0618 to reach the attorney general's staff downstate.