While gasoline prices in the Chicago area remain well below their early summer peak, the high price of crude oil--coupled with recent increases in wholesale gas prices--have some experts worried that pump prices here may begin climbing again soon.

"We see dramatic increases on the wholesale level already," said Bill Fleischli, spokesman for the Springfield-based Illinois Petroleum Marketers Association. "If the wholesale prices keep climbing, it has to be reflected on the retail level."

On Monday, the price for unleaded gas on the wholesale Chicago spot market rose 4.51 cents, to 92 cents a gallon. While Chicago's wholesale prices have lagged those in other parts of the country in recent weeks, Monday's sharp increase helped the Chicago prices overtake those in such places as New York harbor in a single day.

A steep run-up in wholesale gas prices here set the stage for the retail price crunch that plagued Chicago motorists in June, sending gasoline pump prices as high as $2.39 a gallon. And while experts don't expect an increase of that magnitude, the effect of the wholesale increases could nevertheless be felt soon.

Underlying the wholesale gas price increase is the stubbornly high price of crude oil.

Early this week, the price of the basket of crude oils that the Organization of Petroleum Exporting Countries uses to guide its production levels rose to its highest level in the past six months. The price for the OPEC basket rose to $31.22 a barrel on Monday, from $30.44 on Friday.

U.S. officials continue to press OPEC to increase oil production as a way to keep supplies flowing and keep the prices of gasoline, heating oil and other essential petroleum products down. But OPEC says it won't increase production unless the price of its basket remains above a target range of $22 to $28 for 20 consecutive days. As of Monday, the price has been above that level for 11 days.

Even if OPEC nations decide to increase oil production at their Sept. 10 meeting in Vienna, analysts fear that the move would come too late to reduce prices in the U.S. this fall.

Refineries will switch parts of their capacities to the production of heating oil in early September, and that shift--among other factors--is expected to keep the supply of gasoline tight.

Moreover, heavy traffic is expected on the roads this Labor Day weekend, the AAA Chicago Motor Club said, and this, too, may exert upward pressure on prices at the pump. The AAA projects that as many as 33.7 million people will travel over the weekend. "This is up 5 percent from last year, despite gasoline prices being 25 cents per gallon higher than they were in 1999," said Norma Cooper, manager of community affairs at the AAA.

According to the AAA's latest forecast, 28.3 million Americans are expected to use an automobile for trips of 100 miles or longer during the holiday period. "With the economy still going strong," people are electing to travel despite the relatively high price of gas, Cooper said.

In Chicago, the price for a gallon of self-serve regular gasoline averages $1.44 a gallon. This compares with an average of $1.50 nationally. A year ago, the Chicago price was $1.32, versus $1.25 on the national level.

And inventories of crude oil, gasoline, diesel and home heating oil are likely to remain tight, the AAA forecasts. The low inventories have persisted because energy consumption has remained strong while crude oil prices have drifted upward.

According to the Department of Energy, the supply of heating oil is about 40 percent below last year's level. Shortages in New England have been pushing up prices throughout the country. Analysts are warning that the shortages are likely to raise the costs for home heating this winter to the highest level in a decade.