Brent North Sea crude for delivery in December rose 40 cents to $112.82 a barrel approaching midday in London.

New York's main contract, light sweet crude for November, dipped two cents to $92.08 a barrel.

"The oil market continues to be beset with considerable uncertainty, as evidenced by unusual price fluctuations," said Commerzbank analyst Carsten Fritsch.

"Yesterday, for instance, Brent dipped for a time by two dollars to hit $111.50 per barrel, though it has since risen again by one dollar.

The price had already behaved much the same way on Monday."

"Bullish factors such as supply risks and the plentiful supply of liquidity by the central banks are currently counterbalanced by bearish factors such as the supply surplus and subdued demand prospects.

"The price either climbs or comes under pressure depending on which factors happen to be more in focus at a particular time," added Fritsch.

Oil prices eased Thursday as investors digested economic data on slowing growth in China, the world's biggest energy consumer.

They had also fallen at the start of the week as a lower demand outlook offset Middle East supply risks caused by tensions between Syria and Turkey, analysts said.

All eyes Friday were on the EU, whose leaders tackled boosting jobs and growth to mend some of the damage caused by austerity policies, after France and Germany reached a compromise deal on bank supervision key to easing the bloc's crisis.

After an 11-hour session to reach the bank supervision deal, EU leaders were seeking ways to offset the worst effects of spending cutbacks and tax hikes adopted in an effort to tame the eurozone debt crisis.

Violent protests in Greece against more spending cuts and the threat of a general strike in Spain highlighted the risks that unadulterated austerity