The U.S. military said Thursday that homicide bombings fell in November to their lowest level in seven months after joint U.S.-Iraqi operations west of the capital.

In Ramadi, the U.S. military played down reports by residents and police of widespread attacks against American and Iraqi installations there, saying only one rocket-propelled grenade was fired at an observation post and there were no injuries.

An AP Television News video showed the insurgents walking down a shuttered market street and a residential neighborhood, as well as firing four mortar rounds. The masked men, however, appeared relaxed, and the U.S. command dismissed the video as little more than a publicity stunt.

Also Thursday, Iraq's interior minister fired his top official for human rights in connection with a torture investigation. Gunmen attacked Saad al-Obeidi, an adviser to Iraq's defense minister, seriously wounding him along with two of his bodyguards, police said.

Maj. Gen. Rick Lynch told reporters that suicide bombings fell to 23 in November, which he attributed to successful U.S.-Iraqi military operations against insurgent strongholds in the Euphrates River valley west of the capital.

"His weapon of choice is suicide bombers," Lynch said of the insurgents. "In the month of November: only 23 suicide attacks; the lowest we've seen in the last seven months, the direct result of the effectiveness of our operations."

Communities along the river are believed used by foreign fighters to slip into Iraq from Syria, traveling down the river highway toward Baghdad and other major cities.

Nevertheless, Lynch warned that Al-Qaeda in Iraq will likely step up attacks in the next two weeks to try to disrupt parliamentary elections Dec. 15.

Insurgent activity in Ramadi, a turbulent city 70 miles west of Baghdad, appeared aimed at diverting attention from a meeting between U.S. officials and local tribal leaders.

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. U.S. officials disputed the report and said only one grenade was fired.

Residents said that within minutes, scores of masked gunmen, believed to be members of Jordanian-born militant Abu Musab al-Zarqawi's Al-Qaeda in Iraq group, ran into the streets but dispersed after launching attacks with mortars.

The insurgents left behind posters and graffiti saying they were members of Al-Qaeda 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.

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.

Interior Minister Bayn Jabr dismissed Nouri al-Nouri, the ministry's chief inspector for corruption cases and human rights violations, on the order of Prime Minister Ibrahim al-Jaafari, an official said on condition of anonymity because he is not authorized to speak to the media.

Al-Nouri, a Shiite Muslim, had been in the post since the handover of sovereignty to Iraqi in June 2004.

Al-Jaafari, a Shiite, ordered an investigation into the alleged mistreatment of up to 173 detainees after U.S. forces entered an Interior Ministry lockup on Nov. 13 and found that some of those being held showed signs of torture.

Elsewhere, the U.S. command said four American service members had been killed, three of them due to hostile action and the fourth in a traffic accident west of the capital. All deaths occurred Wednesday. The latest deaths raised the U.S. fatality toll for November to at least 85.

The victims included a Task Force Baghdad soldier who died of gunshot wounds, two Marines mortally wounded Fallujah and a Marine from the 2nd Marine Aircraft Wing killed in a traffic accident near Camp Taqaddum, 45 miles west of Baghdad, another military statement said.

The November death toll was below the October figure of 96 — the fourth-deadliest month for U.S. forces since the U.S.-led invasion began in March 2003. But it was more than the 49 killed in September or the 54 in July. Eighty-five U.S. troops died in August.

There was no word Thursday on the fate of five Westerners taken hostage during the past week.

The five include four aid workers from the group Christian Peacemaker Teams — Tom Fox, 54, of Clearbrook, Va.; Norman Kember, 74, of London; and James Loney, 41, and Harmeet Singh Sooden, 32, both of Canada — and German archaeologist Susanne Osthoff, 43.

The British anti-war movement said it is sending one of its leading members, Anas Altikriti, to Iraq to try to secure Kimber's release.

The anti-war movement, which includes the Muslim Association of Britain, Stop the War and the Campaign for Nuclear Disarmament, said it had been following events surrounding the abduction with growing concern.

On Tuesday, Al-Jazeera broadcast video of the four men held by a previously unknown group calling itself the Swords of Righteousness Brigade. The group claimed they were spies working under the cover of Christian peace activists.

The influential Association of Muslim Scholars, a Sunni clerical group, has called for their release.