ABU DHABI ø Al Qaida's operations chief in the Persian Gulf has been killed.

Saudi officials said Abdul Aziz Al Muqrin was shot dead in a clash with Saudi security forces in Riyad on late Friday, the third Al Qaida chief killed in the kingdom over the last year. The officials said Al Muqrin, 33, was killed hours after his Al Qaida cell announced its execution of abducted Lockheed Martin engineer, Paul Johnson, a U.S. national.

On Saturday, Saudi television broadcast footage of Al Muqrin's body and hours later Al Qaida acknowledged his death, Middle East Newsline reported. Three other Al Qaida operatives were also said to have been killed in the shootout in Riyad. The Saudi Interior Ministry identified the operatives as Al Muqrin's deputy, Faisal Al Dakheel, as well as Turki Bin Fuheid Al Muteiry and Ibrahim Bin Abdullah Al Dreiham.

The ministry said Al Muqrin and his aides were in a car that was stopped by Saudi security forces in the Malaz district of Riyad. The Al Qaida operatives fled to a nearby gasoline station and engaged in a shootout with security forces that lasted for several hours. Saudi helicopters were deployed to prevent the escape of Al Muqrin and his cell.

Al Dakheel was believed to have appeared in Al Qaida's video footage in which another U.S. defense contractor, Robert Jacobs, was executed in Riyad on June 12. The Interior Ministry said Al Muteiry was a member of the Al Qaida cell that captured the Oasis compound outside Khobar and executed 22 foreigners on May 29.

Al Dreiham was said to have helped plan and carry out the suicide strike at a foreign housing compound in Riyad in November 2003 in which 17 people, most of them Arab nationals, were killed. Al Muqrin and Al Dakheel were on the Saudi list of top 26 wanted Al Qaida fugitives.

The Interior Ministry said security forces captured three cars used by Al Muqrin, including one used in the June 6 attack on a BBC crew in which a cameraman was killed and a correspondent was severely injured. The ministry said security agents also seized three rocket-propelled grenade launchers, rifles, grenades, forged identity papers and $38,000 in Saudi and U.S. currency.

Saudi authorities were helped by the United States in the search for Johnson. Saudi officials said the FBI sent a 20-member team that specialized in hostage rescue, negotiations, profiling and other fields.

"Our security apparatus is not well trained in combating terrorism, but they are learning," Saudi former Deputy Interior Minister Ibrahim Awaji said.

Al Muqrin was said to have drafted Al Qaida's strategy of targeting Westerners, particularly U.S. nationals, as the most effective means of undermining the Saudi royal family. He was appointed head of the Al Qaida network in Saudi Arabia and the surrounding region after the killing of Khaled Ali Haj in early 2004. Ali Haj succeeded Yusef Al Eiri, killed by Saudi authorities in 2003.

Saudi officials said more than 15,000 Saudi troops had searched for Johnson throughout Riyad on Thursday and Friday. They said officers searched more than 1,200 Saudi homes by the time Johnson, abducted on June 12, was reported to have been killed.

"We did everything we could to find him," Saudi foreign policy adviser Adel Al Jubeir said in Washington. "We are deeply sorry that it was not enough."

The State Department has continued to urge the estimated 30,000 Americans to leave Saudi Arabia. The department said it expected additional Al Qaida strikes on Americans and other Westerners in the kingdom.

"The U.S. government continues to receive credible information indicating that extremists are planning further attacks against U.S. and Western interests," the department said. "Credible information indicates that terrorists continue to target residential compounds in Saudi Arabia, particularly in the Riyad area, and also compounds throughout the country.

Recent incidents indicate that American citizens residing in private residences are also being specifically targeted."