Nymex crude climbed back above $58 Monday after militant attacks on Nigerian energy infrastructure raised fears about supply.
The main militant group in Nigeria's troubled Niger Delta region said Sunday it had blown up two pipelines, carrying out a threat to attack the oil industry after the army destroyed a militant camp.
The impact of the attack on supply is not yet known.
US crude rose by $1.82 to $58.16 a barrel.
For June delivery, light, sweet crude was recently up $1.71, or 3%, at $58.05 a barrel on the New York Mercantile Exchange. July Brent crude on the ICE Futures exchange rose $1.98 to $57.96 a barrel.
Oil has jumped from $32 a barrel in January on hopes for an economic recovery, but it remains well below the record high of $147 touched last July.
Nigeria pumped 1.76 million barrels a day of crude in April, or 2.1% of the world's daily supply, according to the International Energy Agency. About 500,000 barrels a day of its production capacity has been shut in because of technical problems and sabotage.