World oil prices set fresh 13-year highs on Thursday, within a whisker of $40 a barrel for US crude, stoked by worries about summer gasoline shortages in the United States.
Fears of possible sabotage attacks on oil facilities in the Middle East also helped to keep prices strong.
US light crude hit a high of $39.97 a barrel, before easing to trade 27 cents lower at $39.30 a barrel, while London Brent fell 21 cents to $36.51, down from a high of $37.20, which was the highest level since October 1990.
US gasoline futures also eased slightly after hitting another record level of $1.3290 a gallon.
Despite the profit-taking dip, analysts predicted $40-a-barrel oil was still imminent.
"I think we're going to have a four in front of the oil price very soon. It's certainly pretty ugly for the oil consumers of the world," said David Thurtell, commodities strategist at Commonwealth Bank of Australia in Sydney.
Middle East supply security concerns, low US gasoline stocks and rampant demand growth in China have driven US crude prices towards the record $41.15 hit in October 1990 after Iraq invaded Kuwait in the crisis that led to the Gulf War.
"Terrorism fears are causing a permanent risk premium to be built into the market," said independent energy consultant Geoff Pyne.
Traders worry that weekend shootings at a Saudi Arabian petrochemicals plant and attempts a week earlier to bomb Iraq's key Basra oil export terminal might be precursors to a bigger attack on vital oil facilities in the Middle East, which pumps about one-third of global daily crude output.
Tetsu Emori, chief commodities strategist at Mitsui Bussan Futures in Tokyo, forecast that crude was likely to push up to $43-$45 a barrel by mid-year.
"Last year we hit $39.99 before the war, which was largely psychological. Now we need to look at the fundamentals and they are very strong," Emori said. Prices spiked close to $40 during intraday trading in February 2003 as US-led forces prepared to attack Iraq.
Summer US gasoline consumption is at the cutting edge of rising consumption. US refineries are struggling to meet demand that in the past four weeks rose 3.4 percent versus the same period last year to 9.1 million barrels a day, suppressing stocks of the motor fuel well below the five-year seasonal average.
The United States, with less than five percent of the world's population, accounts for some 45 percent of the world's gasoline consumption of just over 20 million barrels daily, US government figures show.
While US motorists are paying a record $1.84 a gallon, retail prices are only a third of average western European levels and have had no impact on demand.