BAGHDAD, Iraq — Insurgents attacked several U.S. bases and government offices with mortars and rockets today before dispersing in the capital of western Iraq's Anbar province, residents and police said.

Iraq's interior minister, meanwhile, fired his top official for human rights in connection with a torture investigation.

The attacks in Ramadi occurred as local tribal leaders and U.S. military officials were to hold their second meeting in a week at the governor's office in the city center. The insurgents apparently tried to shell the building, but reporters inside said there was no damage or injuries.

Police Lt. Mohammed Al-Obaidi said at least four mortar rounds fell near the U.S. base on the eastern edge of the city, but that there were no reports of casualties.

Insurgents also launched mortar rounds at an auditorium in Ramadi where U.S. and Sunni Arab leaders met on Monday, The Washington Post reported earlier this week.

Residents said that scores of masked gunmen, believed to be members of Jordan-born militant Abu Musab al-Zarqawi's al-Qaida in Iraq group, ran into the city's streets today but dispersed after launching attacks with mortars and Russian-made Katyusha rockets.

Life in Ramadi quickly returned to normal after the shooting. The U.S. military said that only one rocket-propelled grenade was fired at an observation post and that there were no injuries or significant damage.

The insurgents did leave behind posters and graffiti saying they were members of al-Qaida in Iraq and claiming responsibility for shooting down a U.S. drone. There were no reports of any U.S. drones being shot down, though.

Ramadi is the provincial capital of Anbar province, a Sunni stronghold, where clashes between insurgents and U.S. and Iraqi troops have left hundreds of people dead in the past two years.

U.S. and Iraqi troops launched a joint operation near Ramadi on Wednesday, sweeping through an area used to rig car bombs.

About 500 Iraqi troops joined 2,000 U.S. Marines, soldiers and sailors in a move to clear insurgents from an area on the eastern side of the Euphrates river near Hit, 85 miles west of Baghdad, the U.S. command said in a statement.

The offensive came as President Bush said he hopes to shift more of the military burden onto the Iraqis as part of a strategy to draw down American forces.

In a statement, the military said the Hai Al Becker region "is suspected to be an al-Qaida in Iraq safe area and base of operations for the manufacture of vehicle car bombs, roadside bombs." It described the area as a transit point for foreign fighters and Iraqi insurgents infiltrating from Syria into Iraq.

There were no reports of casualties during the first day of the operation, part of a series of sweeps through Sunni Arab towns along the Euphrates believed to be major insurgent strongholds.