US benchmark, West Texas Intermediate (WTI) for delivery in July, eased four cents to $104.07 in afternoon trade. Brent North Sea crude for July gained 13 cents to $110.15 per barrel.

Ukraine's interim pro-Western government said Tuesday it had recaptured an airport in the eastern city of Donetsk from pro-Russian insurgents after a day of air strikes and fierce gun battles.

Donetsk mayor Oleksandr Lukyanchenko said two civilians and 38 combatants had died and another 31 were wounded, including Russians and possibly Chechens.

"Traders are still keeping an eye on Ukraine developments especially the continued fighting in the eastern part as well as developments in Libya," said Singapore's United Overseas Bank in a note to investors.

The escalation in tensions comes a day after billionaire chocolate baron Petro Poroshenko was confirmed as the country's new president following weekend polls triggered after pro-Russian leader Viktor Yanukovych was ousted in February.

Washington and its European allies supporting Ukraine's interim government have accused Russia of fomenting unrest in the country, allegations Moscow denies.

Investors fear a full-blown conflict in the ex-Soviet state, a conduit for a quarter of European gas imports from Russia, will disrupt supplies and send energy prices soaring.

Kelly Teoh, managing director at IR Resources in Bangkok, said prices were also supported by hopes of a further drop in US crude stockpiles, indicating robust demand in the world's top crude consumer ahead of the busy summer driving season.

US crude stocks plunged 7.2 million barrels in the week to May 16, the Department of Energy revealed last week.

The weekly stockpiles report will be released on Thursday instead of Wednesday this week, because of the Memorial Day holiday weekend.