Treading into yet another flashpoint city, U.S. Marines and Iraqi security forces began a series of raids Tuesday on mosques in and around the Sunni city of Ramadi following an upsurge in the use of mosques for insurgent activity, the military announced.

Also Tuesday, the military resumed air strikes in nearby Fallujah, said to be the hideout of the terrorist network run by Abu Musab Zarqawi, a Jordanian-born militant responsible for numerous bombings, kidnappings and beheadings, according to Iraqi and U.S. officials.

The military said it hit a center for Zarqawi "terrorist meetings" in one strike and a "known terrorist safe house" in another. The safe house was being used by Zarqawi associates at the time of the strike, a statement said.

Wire service reports said at least one of the buildings hit was a restaurant. The Associated Press reported that five people died in the strike on the restaurant.

The mosque raids in Ramadi followed two days of clashes in the city, 70 miles west of Baghdad. Insurgents reportedly fired two mortars at the city hall and a police station Monday night.

The military took pains Tuesday to explain the mosque raids, issuing a statement detailing recent attacks in which a mosque was used as a base or refuge.

Most recently, the Marines said they were attacked Monday from the Sharqi Mosque in the city of Hit near Ramadi, with insurgents engaging in a three hour firefight using small arms, machine guns and mortars.

Marine air strikes were called in to end the battle, the military said. Wire services reported that the mosque caught fire after the fight.

Officials also cited an Oct. 8 attack by insurgents on the Red Crescent Society building in Ramadi, after which the attackers took refuge in a mosque.

U.S. military officials stressed that American forces were used to back up Iraqis.

Brig. Gen. Joseph F. Dunford of the 1st Marine Division said in a statement that the mosques are suspected "of participating in a spectrum of insurgent activity, including harboring known terrorists, storing illegal weapons caches, promoting violence against the Iraqi people and encouraging insurgent recruitment."

He said the raids were search missions, aimed at "known terrorists and insurgents" as well as weapons.

"Mosques are granted protective status unless they are being used for militant purposes," said Dunford. "At that time they lose their protective status as places of religious worship."

Angry residents were unreceptive to the explanations, according to wire service reports from the scene. "This cowboy behavior cannot be accepted," cleric Abdullah Abu Omar of the Ramadi Mosque told the Associated Press.

In other developments, the chairman of a Turkish construction company whose employees were released by kidnappers said Tuesday his firm will not withdraw from Iraq because it was unclear whether the abductions were politically motivated, the A.P. reported.

Ten employees of the Turkish firm VINSAN were freed by their abductors and arrived at the Turkish embassy in Baghdad. All were said to be in good health.

"We will not withdraw from Iraq," Ali Haydar Veziroglu, VINSAN board chairman, told reporters at his Baghdad offices, citing uncertainty about whether the kidnappers were insurgents or criminals. "Are they a political network or not a political network?"

Veziroglu, speaking through an interpreter, refused to say whether any ransom was paid but added that "people from civil society and clerics" helped mediate the release.

"I'm sure they had erroneous information," he said of the kidnappers, who identified themselves as the Salafist Brigades of Abu Bakr al-Siddiq. "As a result of dialogue with them, they accepted the facts we offered and knew that our company was rendered an injustice."