Oil futures slipped this morning in modest profit taking from a surge late last week on jitters over Nigerian output.
But losses were checked by refinery outages and signs that Opec's supply cuts were helping drain stockpiles.
Front-month US crude for March delivery was down 26 cents at $59.13 a barrel on the Globex electronic trading platform after falling to as low as $58.87. London Brent crude was trading down 10 cents at $58.85 a barrel.
Traders said activity was likely to be muted as the NYMEX floor is closed today due to the Presidents Day holiday.
Prices surged $1.40, or 2.4 per cent, on Friday after the United States warned that militants from Nigeria's oil-producing delta plan to expand their attacks on foreign nationals beyond the Niger Delta region.
Violence in the delta over the past year has already cut output from Africa's top producer by a fifth, and analysts fear it may escalate ahead of presidential elections in April.