Saudi anti-terrorism forces killed al Qaeda's top leader in the Persian Gulf kingdom in a gun battle Sunday, but experts warned that Saudi Arabia still faces a surge in attacks despite its two-year crackdown on extremists.

Officials said a 90-minute battle in the eastern Rawdah district, an upscale neighborhood in Riyadh, was the latest blow dealt to Osama bin Laden's group in Saudi Arabia, a U.S. ally. Many of al Qaeda's leaders have either been killed or captured since authorities launched an offensive against the group in 2003.

Younis Mohammed Ibrahim Hayari, a Moroccan, was killed in a dawn raid by security forces in an area where suspected extremists were hiding, according to an Interior Ministry official quoted by the state-run Saudi Press Agency.

Three other suspects were arrested, a security official said, speaking on condition of anonymity because of the sensitivity of the issue. He said Hayari and the three other men were on a list of Saudi Arabia's 36 most wanted terrorists that was issued Tuesday.

The government news agency, quoting an unidentified official, reported that Hayari headed al Qaeda in Saudi Arabia.

Hayari "was nominated by his peers . . . to be the head of sedition and corruption in the land." the official said.

On Wednesday, the Saudi interior minister, Prince Nayef, warned of the possibility of more attacks.

Security forces "killed the leader less than four days after they issued the list. That is a major victory, both on the intelligence and the logistical levels. It's a major intelligence breakthrough," said Mustafa Alani, a terrorism expert at the Gulf Research Center in Dubai.

He claimed that the terror group had a leadership crisis and that Hayari's killing would hinder the group's operations.

"There is clearly a leadership vacuum in the kingdom for Saudi Arabia and this will demoralize the members who are in hiding," he said.

Hayari was believed to have had close ties to Abdul Karim Majati, an al Qaeda leader killed in April.

The Interior Ministry official said security forces conducted two simultaneous operations in eastern Riyadh to capture suspects and killed Hayari after a shootout.

This oil-rich kingdom has suffered a series of attacks since May 2003, when suicide bombers attacked three compounds housing foreigners in Riyadh. Saudi security forces then launched a wave of retaliatory raids against the extremists, and in December 2003 issued a list of 26 most wanted suspects; 23 of them have reportedly been killed or captured.

Saudi security forces secure an area of Riyadh, the capital, after a 90-minute gun battle with suspects named in a Saudi most wanted list.Younis Mohammed Ibrahim Hayari was said to be al Qaeda's leader in Saudi Arabia.