Al-Qaida purportedly claimed responsibility for Friday's sucide bombing attack on the world's largest oil processing facility, the first on an oil facility in Saudi Arabia.
The claim was posted on a Web site frequently used by terror groups but there was no way to check its authenticity.
The assault raised speculation that the terrorists were adopting the tactics of insurgents across the border in Iraq, where the oil industry has been repeatedly targeted.
The would-be bombers were stopped from breaking in by guards who fired on their cars, exploding both vehicles and killing the attackers.
This "is part of the project to rid the Arabian Peninsula of the infidels," the statement read.