New York's main contract, light sweet crude for February delivery, was up 97 cents to $89.00 per barrel.
Brent North Sea crude for February rose 72 cents to $94.05.
"Crude is moving towards $90 a barrel as there is some uncertainty in the market as to when the pipeline will reopen," said Ong Yi Ling, investment analyst for Philip Futures in Singapore.
US media reports said the trans-Alaska pipeline remained shut after a leak, discovered Saturday, at a pump station. The pipeline carries between 630,000 and 650,000 barrels of crude.
On Friday, crude prices fell as a stronger dollar made the commodity more expensive and a closely watched US unemployment report came in below expectations.
The US Labor Department reported a sharp drop in the unemployment rate in December to 9.4 per cent, but at the same time, the economy created 103,000 jobs, much fewer than the 150,000 forecast by analysts.
The United States is the world's biggest oil-consuming nation.
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