Brent crude futures eased towards $105 a barrel, falling from an 11-week high, as investors cautiously awaited guidance from the U.S. Federal Reserve on its economic stimulus plan.
The Fed, whose two-day policy meeting starts on Tuesday, is under pressure to pare back some of its $85 billion in monthly bond purchases after advances in the U.S. economy.
Its three quantitative-easing schemes have buoyed prices of commodities as they pumped liquidity into the market and lowered the value of the dollar, making greenback-traded commodities cheaper for investors in foreign currencies.
At 1107 GMT, Brent was down 17 cents at $105.30 per barrel. It rose to 106.67 on Monday, the highest since April 4, on mounting tensions in the Middle East.
U.S. oil dipped 22 cents to $97.55 after hitting a nine-month high near $99 a barrel in the previous session.
"Yesterday was largely a response to the slight escalation in Syria and you would expect a bit of and easing off if nothing new happens," said Simon Wardell, analyst at Global Insight.
"If the Fed takes away the stimulus, it will boost the dollar and potentially push oil prices down, but a lot has been priced in already. The Fed will try to do it as gradually as possible to avoid a shock so the impact on oil will probably be minimal," Wardell added.
Global financial markets have been on edge since Fed Chairman Ben Bernanke suggested the central bank would be looking to taper its stimulus.
The oil market is also keeping an eye on a standoff over the civil war in Syria as world leaders lined up to pressure Russian President Vladimir Putin into toning down his support for Syrian President Bashar al-Assad on the second day of a G8 summit.
Although Syria is not key to global oil supply, investors are worried the civil war there could affect other countries in the Middle East and plunge the whole region into conflict.
Stung by recent victories for Assad's forces and their support from Hezbollah guerrillas, the United States said last week it would step up military aid to the rebels.
"If anything should have an impact on the oil prices, it should be the easing of tensions in the Middle East," Wardell said.
The election of a moderate Iranian president Hassan Rohani could further ease tensions in the region.
"We do not expect the embargo on Iranian crude exports to be lifted any time soon, even though the dialogue will probably improve after the hard-line approach taken by Rohani's predecessors," Andrey Kryuchenkov of VTB Capital said.
U.S. commercial crude oil stocks likely fell last week due to lower imports, according to a preliminary Reuters poll on Monday.