The ministry said Fahd Faraj al Juwair, the alleged leader of al Qaeda in Saudi Arabia, Ibrahim al Mutair and Abdullah al Shammari were on the list of 36 most wanted al Qaeda militants issued by the Saudi authorities in June. Jaffal al Shammari and Suleiman al Talq were also killed. All five were Saudi nationals. The identity of a sixth man captured in the clashes has yet to be revealed.

Juwair, Jaffal al Shammari and Abdullah al Shamri, who were killed by the security services, in Riyadh’s Yarmouk neighborhood, took part in the foiled suicide attack on the major oil processing facility at Abqaiq on Friday, the ministry added.

The attack, the first direct assault on Saudi oil production, was stopped when guards fired on cars packed with explosives trying to force entry. At least two vehicles blew up killing the occupants. Two guards were also killed and other two injured. The three militants were in a Land Cruiser car that sped away from the scene.

The investigation into the Abqaiq attack led the security forces to a safe house in the Yarmoul neighborhood of the capital, used by the militants as a base. Early on Monday, security forces besieged the house and exchanged fire with the five militants who were armed with machine guns and hand grenades. The militants barricaded themselves behind two cars, one of which was later identified as having been used in the attack on the oil production facility.

Born in al Zulfi, the 36-year-old Juwair was number two on the list. He took over the leadership of al Qaeda in Saudi Arabia in July following the death of Younis al Hayari, a Moroccan, in a shootout in Riyadh . No 11 on the list of most wanted, Ibrahim al Mutair was a computer expert while Abdullah al Shammari, No 15, who assisted al Qaeda with transportation, had previously been detained by the authorities but released after he and his family promised to distance themselves from extremism.

For his part, Jaffal al Shammari, aged 28, was previously arrested for his links to al Qaeda and was known to be obtaining information about bomb making.

The Ministry statement added that 21-year-old Suleiman al Talq had been active on extremist internet forums.

Security services seized weapons, ammunitions, supplies, explosives, money, documents and other items.