Two fighters were killed in the attack after Saudi security forces fired on bombers attempting to drive two cars packed with explosives through the gates of the facility.

Saudi television aired parts of a tape apparently made by the attackers showing them preparing the two vehicles used.

It said the tape and about 1.5 tonnes of explosives were found in a depot outside the capital, Riyadh, last week.

It also showed pistols, assault rifles, a computer and various videotapes it said were recovered by police.

 

One of the five people arrested is reported to be on Saudi Arabia's most wanted list.

 

The attack in Abqaiq, the world's largest oil facility, was the first major strike in Saudi Arabia since bombers tried to storm the interior ministry in Riyadh in December 2004.

The prospect of a direct attack on Saudi crude facilities has long concerned 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.