Oil prices have hit record highs in the United States for the third straight day in early trading Thursday, amid continuing concerns about the supply of crude oil.
U.S. light crude futures rose by 51 cents, to reach a record $52.53 a barrel, before dropping back slightly.
The oil industry is still recovering from Hurricane Ivan, which knocked off-line almost 30 percent of oil production in the Gulf of Mexico.
Sabotage in Iraq, political unrest in Nigeria and a tax dispute involving a major Russian oil firm also threaten to cut into supplies at a time of strong demand. U.S. oil stocks are at lower than projected levels heading into winter.
But while prices have risen about 50 percent in the last year, they still remain - adjusted for inflation - below highs reached after the 1979 Iranian revolution.