Oil prices briefly bolted above $45 a barrel Thursday, then retreated toward $44, in a volatile day of trade after Russian oil giant Yukos (search) said its output could suffer because of a court ruling that froze some of its assets.

The company's comments heightened supply fears that had been raised a day earlier after government and industry data showed a sharp decline in U.S. oil inventories.

After prices jumped as high as $45.37, traders began locking-in profits as analysts voiced skepticism toward the dire picture painted by Yukos Oil Co., which owes the Russian government $3.4 billion in back taxes for 2000.

"We haven't lost a single barrel of oil from Yukos yet," said John Kilduff, senior analyst at Fimat USA in New York.

Light crude for October delivery settled at $44.06, a gain of 6 cents, on the New York Mercantile Exchange (search). It was the second day in a row that oil prices rose.

Crude futures advanced $1.88 Wednesday after the Energy Department (search) reported that commercial inventories of crude fell by 4.2 million barrels to 287.1 million barrels last week — a surprise to most traders, who expected inventories to be steady or grow slightly.

This latest move higher follows a sharp retreat from the peak Nymex settlement of $48.70 that was reached Aug. 19.

On an inflation-adjusted basis, prices are about $13 below the level reached leading up to the first Gulf War.

Underlying the market's jitters about potential supply disruptions is the fact that there is only a thin margin — perhaps 1 percent — of spare output capacity worldwide. Daily global oil demand is roughly 82 million barrels, according to several analysts.

Yukos produces roughly 1.7 million barrels per day — an amount equal to about one-third of Russia's daily exports. The company has repeatedly said that the government's actions against it have jeopardized output.

While these comments have stoked global supply concerns, most analysts do not believe Russian President Vladimir Putin would allow crude production to drop because oil accounts for much of the country's budget.

Still, when coupled with the sabotage of oil infrastructure in Iraq that sporadically impedes exports, its role as a market force has been magnified.

There were reports out of Iraq on Thursday that saboteurs had detonated explosives on an oil pipeline near the northern city of Kirkuk. The pipeline links oil fields near Kirkuk with a refinery. Officials with the state-run North Oil Co. could not be reached for comment.

In London, Brent crude for October delivery rose 10 cents to settle at $41.57 on the International Petroleum Exchange (search).

In other Nymex trading, heating oil futures rose 0.14 cent to $1.1839 per gallon, while gasoline futures inched 0.42 cent higher to $1.1932 per gallon.

Natural gas for October delivery dropped 19.8 cents to $4.767 per 1,000 cubic feet as traders displayed comfort with current supply levels.