Oil prices hit four-month highs on Friday driven by new Middle East turmoil and the promise of stronger growth from the Federal Reserve's new QE3 stimulus plan.
In New York the benchmark contract, West Texas Intermediate crude for October delivery, passed the $100 mark before slipping back in late trade to $99.00 a barrel, up 69 cents from Thursday.
London's Brent North Sea contract for November delivery ended at $116.66 a barrel, 78 cents higher from Thursday.
In London morning deals, Brent hit $117.95 a barrel, touching the highest level since early May.
The Fed's announcement Thursday of new, open-ended stimulus -- a quantitative easing bond-buying program -- sent the dollar lower and boosted expectations for oil demand.
"The Fed's announcement has caused crude oil prices to climb to multi-month highs," said Commerzbank analyst Carsten Fritsch.
The spread of anti-US demonstrations across the oil-rich Middle East and further afield also added to worries that the flows of crude from the oil-rich region might be affected.
"Supply risks are lending psychological support" to oil prices, said Fritsch.
"This region, which is so crucial to the supply of oil, is thus far from stable, something that is likely to give rise to a lasting risk premium."