In morning trade, New York's main contract, light sweet crude crude for November delivery, was down eight cents at USD 86.03 a barrel, extending sharp falls in New York after a glum assessment of the US Federal Reserve.
Brent North Sea crude for December was up 21 cents to USD 108.60 after reports of renewed threats to oil production in Libya from forces loyal to ousted leader Muammar Gaddafi.
Analysts said the overall mood was being dictated by economic worries, with investors waiting for results of a summit by European leaders this weekend on how to prevent the debt crisis from further escalating.
Initially limited to Greece, Europe's almost two-year-old debt crisis has spilled across borders, threatening large economies as well as the continent's banks.
"Markets will look to this weekend's European economic summit for some signs that a workable plan can be crafted to reduce the market stress," said Sanjeev Gupta, head of the Asia-Pacific Oil