Crude oil prices hit their highest level in three months Tuesday in New York.
Crude oil for future delivery rose as high as $65.53 a barrel.
Traders said they are worried that tensions in Iran and Nigeria could crimp already-tight oil supplies, while experts predict oil demand will continue to grow.
Iran and Nigeria produce about 7.5 percent of the world's oil.
Iran is in a dispute over its alleged efforts to build nuclear weapons, and experts say it might respond to possible sanctions by stopping delivery of the more than two million barrels of oil it exports daily. Nigeria's output is hampered by the kidnapping of oil workers.
Meantime, experts predict demand for oil will grow more than two percent this year to more than 85 million barrels a day.