Brent oil kept gains near six-month highs on Wednesday, as fears of supply disruptions from Iran, other Middle Eastern producers and Africa outweighed worries about the global economy.
But concerns about the outcome of Greek bailout talks in Brussels among euro zone officials limited the day's rises.
Data showing a surprise drawdown in U.S. oil inventories last week, however, helped firm crude futures.
"The oil markets are doing a balancing act between what's happening in Iran and the euro zone, where the Greek bailout deal may still fall apart," said Chris Dillman, analyst at Tradition Energy in Stamford, Connecticut.
At 2:45 p.m. EST (1945 GMT), ICE April Brent crude traded in London at $118.98 a barrel, up $1.63. It climbed early to a session peak of $119.99, the highest intraday since Aug. 1, on the report that Iran was halting oil exports to some EU countries.
U.S. March crude settled at $101.80 a barrel, gaining $1.06, the highest close since Jan. 11. It hit an early peak of $102.54, the highest intraday since Jan. 12.
Brent's total crude oil volume rose 17 percent above its 30-day average, Reuters data showed. U.S. crude volume was up 1.0 percent against its 30-day average.
"Bubbling of tensions with Iran will always be supportive of the oil price, and this latest development is no different," said Harry Tchilinguirian, analyst at BNP Paribas.
U.S. crude oil inventories showed a surprise, if modest, drop of 171,000 barrels in the week to Feb. 10, defying the forecast in a Reuters poll for a 1.5 million-barrel increase and going against industry data released late on Tuesday showing a 2.9 million-barrel build.
Crude stocks held at the Cushing, Oklahoma, delivery hub for U.S.-traded crude oil futures rose to their highest level since September, posting a 2 million-barrel build, the biggest weekly increase since December 2009.
The gain in Cushing stocks helped widen Brent's premium against U.S. crude to around $16.70 a barrel. The gap had narrowed on Tuesday to $16.27. <CL-LCO1=R>
Oil-supply risks far outweigh the effects of the euro zone's debt problems, highlighted by the still-unresolved quest of Greece to obtain a second debt bailout.