World oil prices rose again today, hitting new historic highs because of a security scare in Saudi Arabia, the world's biggest crude exporter, while supply concerns persisted in the United States. New York's main contract, light sweet crude for delivery in September, rose 17 cents to 64.11 usd per barrel after striking an all-time high of 64.27 usd per barrel overnight. In London, the price of Brent North Sea crude oil for delivery in September rose 10 cents to 62.80 usd after earlier hitting a record 63.06 usd per barrel. Continued strong demand in the United States, in the midst of its summer driving season, along with renewed worries of a terrorist attack in Saudi Arabia are combining to push prices to fresh record levels, dealers said. "There are fundamental reasons for a strong market," said Tony Nunan, manager for energy risk management at Mitsubishi Corp's international petroleum business in Tokyo. "There are many geopolitical risks, yet there is no slack in the system to handle any disruptions," he said. The US embassy warned on July 20 that terrorists could strike again in Saudi Arabia, which has been rocked by a spate of bloody attacks attributed to Al-Qaeda militants in the past two years. In London, the Foreign Office said yesterday it has "credible reports" that terrorists are in the "final stages" of planning attacks in Saudi Arabia. Saudi Arabia is the world's biggest oil exporter, producing about 9.5 mln per day and has the capacity for an additional daily quota of 1.5 mln. It is seen by many analysts as the only oil exporter with significant capacity to spare. Disruptions at US refineries were also a factor behind the recent spike in prices as oil companies battle to provide sufficient gasoline and heating fuel to meet robust demand, particularly from the northern hemisphere. The failure by oil giant ExxonMobil Corp to restart its 245,000 barrels-per-day refinery in Joliet, Illinois as scheduled last Thursday, was particularly compounding worries of a supply disruption, dealers said. Oil prices are around 40 pct higher than a year ago. However adjusted for inflation, they remain far below levels reached in the wake of the 1979 Iranian revolution when prices surged to upwards of 80 usd a barrel in today's money.