New York's main contract, light sweet crude crude for December delivery, was up 30 cents to USD 86.37 a barrel, and Brent North Sea crude for December jumped eight cents to USD 109.84.
Traders were monitoring developments in oil-producing Libya after ousted former leader Gaddafi was killed, with a focus on how fast the country will restore production that was lost during the rebellion.
Libya was producing about 1.4 million barrels per day of mostly high-value light sweet crude before the uprising at the start of the year.
Around 85 per cent of Libyan output was exported to Europe, and the break in supply contributed to a surge in Brent.
However, Phillip Futures said in a report: "While North Sea production problems have been supportive to oil prices and Brent in particular, traders and analysts expect the return of Libyan oil exports to continue, unaffected by the death of Libya's ousted leader Muammar Gaddafi."
Oil cartel OPEC sees member Libya restoring production to one million barrels per day within six months, then attaining pre-conflict levels by the end of 2012. Traders were also bracing for the outcome of European Union summits on Sunday and Wednesday.
EU leaders decided to hold a second summit on Wednesday as France and Germany continue to bicker over the best way to boost a support fund for troubled economies, hurting chances of an agreement on Sunday.