Oil prices turned higher in late trade Friday to end with modest gains ahead of the weekend despite growing worries over deficit negotiations in Washington.
In New York, West Texas Intermediate crude for January delivery added 84 cents to $88.91 a barrel.
On the London market, the Brent North Sea contract for January gained 47 cents to $111.23 a barrel.
Traders said there was little news to explain the higher price; the rising euro, which topped $1.30, was one likely contributor to buying.
But the US fiscal cliff talks, which could see the world's largest economy forced into recession next year if Democrats and Republicans cannot agree on a deficit-cutting plan, continued to overshadow trade.
Politicians on both sides signalled Friday that things were not going very well in the talks, one month before the deadline.
"Crude oil prices consolidated within the recent range... due to the mixed signals from the US about the fiscal cliff program and the ongoing uncertainty about the eurozone's economic conditions," said Sucden Financial Research analyst Myrto Sokou.
In Europe, official data published Friday showed unemployment in the eurozone hit a record high in October, another drag on growth in the region.
In Lagos, ExxonMobil's Nigeria chief warned that Nigerian oil production will fall by 40 percent by 2020 if the country goes ahead with proposed increases in taxes and royalties.
The proposals are part of a planned sweeping overhaul of Nigeria's oil industry that has been delayed for years. It would also include a restructuring of state oil firm NNPC.
Mark Ward said the current legislation included fiscal terms that were too harsh and would block investment.
"It would be good to have a good (law) passed so there is clarity and there is certainty on the investment climate, the fiscal terms as well as the restructuring," Ward told a gathering of industry figures.
"However, if what we see today is passed without significant changes, it will cause just the opposite: investment will dry up."