Oil prices have risen by more than 1% a barrel as the main pipeline in Alaska remained all but closed for a third day following a minor leak.
Since Saturday only 5% of typical output has flown through the Trans-Alaska Pipeline following a spillage at one of its pump stations.
The pipeline is important because it carries almost 12% of US crude output.
US light crude ended up $1.22 or 1.4% a barrel at $89.25. Brent crude rose $2.37 to settle at $95.70.
The Alaska Department of Environmental Conservation said no restart date had been set, but the plan was to build a bypass pipeline for the section in question.
The 800-mile (1,280km) Trans Alaska Pipeline is operated by Alyeska Pipeline Service, and typically carries 630,000 barrels per day.
Alyeska is 47% owned by BP, while ConocoPhillips has a 28% stake, and ExxonMobile 20%.
Oil analysts said US authorities would not rush to give clearance to allow output to restart at full levels, such is the intensified focus on safety following last April's major oil spill in the Gulf of Mexico.