Oil futures rose slightly but stayed below the $48 mark Thursday, after falling sharply on U.S. petroleum inventory data showing more strong growth in crude stocks.

The market was sobered by Department of Energy (search) figures that revealed a build of 334 million barrels in the week ending May 13 from the previous week — the 13th increase in the past 14 weeks — up 34 million barrels from a year ago. The total crude inventory figure was the highest since May 1999, when compared to monthly data.

After dipping as low as $46.80, light, sweet crude for June rose 15 cents in afternoon trading on the New York Mercantile Exchange (search). The contract had fallen $1.72 on Wednesday following the release of the stocks report.

On London's International Petroleum Exchange (search), July Brent rose 15 cents to $48.30 a barrel.

"We were down for literally days quite substantially ... It doesn't surprise me that we needed a day to bounce a bit," said James Steel, director of oil research for Refco Group Inc. Steel said he expects crude prices to continue falling in the long-term.

Meanwhile, refined product futures rose when traders were briefly spooked by news that production of gasoline and other oil products at France's Total SA dropped, as a labor strike at five of its six refineries entered its fourth day.

Heating oil rose 3.58 cents to $1.3940 a gallon, while unleaded gasoline rose nearly 2 cents to $1.4330 a gallon.

Wednesday's inventory report showed oil products building at a slower clip than anticipated. Gasoline stocks rose by 1.1 million barrels to 214.8 million barrels, heating oil stocks rose by 200,000 barrels to 38.1 million. Meanwhile, distillates fell 200,000 barrels to 103.8 million.

Energy Security Analysis Inc.'s Rick Mueller said gasoline supplies rose primarily because of higher refinery output and imports, adding: "Demand will return in strength ... as retailers ensure their tanks are full in time for the traditional end-of-May start of the summer driving season."

The Energy Department said U.S. refiners ran at 94.0 percent capacity, up from 91.8 percent a week ago. With refiners approaching peak capacity, analysts worry that the facilities may not be able to cope when demand — especially for gasoline — rises in summer.

There are also worries about possible refinery outages when production of heating oil is ramped up ahead of the Northern Hemisphere's next winter.

But chief analyst Ehsan Ul-Haq of PVM Oil Associates in Vienna said that — for now — less-than-expected appetite for gasoline would likely keep prices in check.

"Gasoline demand in the U.S. ... is strong, but not as strong as expected previously," he said. "People are thinking twice before buying a new SUV, and people are driving less because of higher prices."

Additionally, he said prices are being weighed down by Saudi determination "to send as much oil as possible before the second half of the year," which is traditionally a period of higher demand.

Recent data from Washington and the Paris-based International Energy Agency (search) appears to back comments from OPECoil ministers who repeatedly say that markets are well-supplied. The Organization of Petroleum Exporting Countries is already pumping at full-tilt, at nearly 30 million barrels daily, to steady prices and calm fears about the group's excess capacity.

But PVM forecast higher demand in the second half of the year, in part because of China's hunger for crude and oil products.

April data showing a 23 percent increase in crude imports by China over the year defies "recent statements that demand growth (there) is slowing much faster than anticipated," the report said.