Oil prices have vaulted to an all-time high amid fears that disruption to Middle East oil flows may stress world fuel supplies already eroded by strong demand growth in China and the United States.
US light crude jumped to a record $41.17 a barrel, its highest in the 21 years since the New York Mercantile Exchange launched the contract in 1983.
London Brent stood at $38.24, down 25 cents, after scaling to a 13-year peak at $38.53 a barrel on Thursday.
Allowing for inflation, prices are about half those during the oil price shock that followed the 1979 Iranian revolution. Crude's historic peak adjusted for inflation was a $78-a-barrel average in 1980, according to BP.
Dealers said crude's rally was led by a rise in US gasoline futures to a record $1.4015 a gallon after government data showed stocks shrinking at a time when refiners try to build inventories ahead of rising summer demand.
Strong global economic growth is also causing oil demand to increase faster than expected while upheaval in the oil-rich Middle East and doubts about whether the OPEC cartel can cool the market have helped support prices.
The Organisation of the Petroleum Exporting Countries (OPEC) will decide output policy on June 3rd in Beirut after discussing options on the sidelines of a forum for petroleum producer and consumer countries in Amsterdam on May 22-24.
Already pumping more than two million barrels a day in excess of its official limits, traders say OPEC's proposed increase in quotas of at least 1.5 million bpd will do little more than legitimise existing production.