RIYADH, Feb 24 (Reuters) At least two cars exploded at the gates of Saudi Arabia's huge Abqaiq oil facility today when security forces fired on suicide bombers trying to storm the world's biggest oil processing plant, Saudi officials said.
Saudi state television said oil output was unaffected. Oil prices had jumped 2 dollars a barrel on news of the attacks against the world's largest oil exporter and a key U.S. ally.
''Security forces foiled an attempted suicide attack at the Abqaiq refinery using at least two cars,'' an official said.
It was the first direct militant strike against crude oil facilities since Al Qaeda militants launched a campaign of suicide bombings aimed at toppling the kingdom's pro-Western leaders in May 2003. It came a year after Al Qaeda leader Osama bin Laden urged supporters to hit oil targets in the Gulf.
''The damage was only limited to a fire, which was brought under control immediately. Production operations were not affected,'' Saudi Arabia's Interior Ministry said.
The prospect of an Al Qaeda attack on Saudi Arabia has been a doomsday scenario for oil consumer nations heavily reliant on Saudi oil. The kingdom accounts for around a sixth of the world's oil exports, supplying 7.5 million barrels a day.
Saudi security adviser Nawaf Obaid said Saudi security forces fired on three cars packed with explosives as they rammed the outer gates of the facility, 1.5 kilometres (one mile) from the main entrance. He said the three cars exploded.
''Three cars rammed the first of the three sets of gates protecting Abqaiq and when security shot at them all three cars exploded,'' Obaid said.
Dubai-based television station Al-Arabiya said the attackers had been killed. It added the cars they used had the logo of Saudi state-owned oil company Aramco. Al Arabiya also said a fire at a pipeline from the blast was now under control.
Most Saudi oil is exported from the Gulf via the huge producing, pumping and processing facility at Abqaiq, also known locally as Baqiq, in the kingdom's mainly Shi'ite Eastern Province. The world's biggest processing plant, it handles about two-thirds of Saudi output.
SPECTACULAR TARGET Former Middle East CIA field officer Robert Baer has described Abqaiq as ''the most vulnerable point and most spectacular target in the Saudi oil system.'' Abqaiq handles crude pumped from the giant Ghawar field and ships it off to terminals Ras Tanura -- the world's biggest offshore oil loading facility -- and Juaymah.
''It's not clear what damage there is but Abqaiq is the world's most important oil facility,'' said Gary Ross, CEO at PIRA Energy consultancy in New York.
''This just emphasises fears over global oil supply security when we're already facing major ongoing risks in Nigeria, Iran and Iraq.'' There have been several attacks on foreign workers in Saudi Arabia in recent years but oil output has escaped unscathed.
In May 2003, at least 35 people were killed and 200 wounded in suspected al Qaeda suicide bombings on compounds in Riyadh.
A year later militants attacked oil company and housing compounds in Khobar, then fled to the city's Oasis housing compound, taking hostages. Seven Saudi policemen were killed.
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