Government troops began house-to-house searches for Al Qaeda in Iraq militants in Mosul Thursday, part of a major security operation to cleanse Iraq's third-largest city from cells of the terror network.

Prime Minister Nouri al-Maliki flew to Mosul Wednesday to take charge of the operation by U.S.-backed Iraqi forces. Described by the U.S. military as the last major urban base of Al Qaeda in Iraq, Mosul has become the site of al-Maliki's third security drive in two months as he attempts to defeat Shiite militants and Sunni extremists.

On Thursday, he sought to enlist the support of former Saddam Hussein-era army officers and local tribal leaders in two separate meetings in Mosul.

Mosul has traditionally supplied the army with a large number of its officers and al-Maliki called on authorities to help bring back those who wish to return to duty, according to a statement issued by his office.

The prime minister, who has been vigorously courting tribal leaders in recent months, also appealed to dignitaries from local tribes to stand behind his security forces in the fight against militants.

"We came to restore the dignity of the law and the state in the city," al-Maliki told the tribesmen, adding that the campaign's goals were to rid the city of Al Qaeda, improve services and reconcile its religiously and ethnically diverse population.

However, Al Qaeda, which has been weakened by the U.S. troop buildup over the past year, appears to be far from defeated.

In an attack that bore the group's hallmarks, a homicide bomber Wednesday blew himself up in a funeral tent in a village west of Baghdad, killing 22 people and wounding 40, according to police Col. Faisal al-Zubaie.

The funeral for Taha Obaid, a primary school principal killed the previous day by gunmen, was attended by local U.S.-backed Sunni tribesmen fighting Al Qaeda militants. It was not known how many of them were among the killed and wounded.

Obaid's 3-year-old son was among those killed, said al-Zubaie.

In Baghdad, a fragile cease-fire reached this week between Shiite politicians and followers of anti-American cleric Muqtada al-Sadr in the Sadr City district came under renewed strain Thursday.

Overnight and early morning clashes between U.S.-backed Iraqi forces and militiamen loyal to al-Sadr left eight men killed and 19 wounded, according to officials from two hospitals in the Shiite enclave.

The officials, speaking on condition of anonymity because they are not authorized to speak to the media, said the wounded included women and children.

The U.S. military, meanwhile, said two militants were killed and a third was wounded late Wednesday by an air-to-ground Hellfire missile as they placed a roadside bomb on a road between Sadr City and the northern Sunni district of Azamiyah.

In Sadr City, one person was killed when another Hellfire missile hit a group of militants also attempting to plant a bomb, the military said. The rest of the group fled when they heard the U.S. helicopter gunships approaching Wednesday night.

Also in Baghdad, police officials said a roadside bomb struck the convoy of the capital's Shiite governor, Hussein Tahan, as it made its way to pick him up from his home in the central Karradah district. One of his bodyguards was killed in the blast and six others — four other bodyguards and two bystanders — were wounded.

The blast went off in the morning in central Nasr Square.

In Mosul, the government on Thursday eased round-the-clock restrictions on movements that have been in force since May 10. Residents had been barred from leaving their neighborhoods on foot or in vehicles.

Under the latest decision, the restrictions would be in force only between 6 p.m. and 6 a.m. A total ban on motor bikes and trucks will stay in force.

There were no reported clashes during the house-to-house searches in known Al Qaeda strongholds in the western and eastern parts of the city. Al Qaeda militants had in the past fled from areas where they expected a security crackdown and reappeared elsewhere from which they launch renewed attacks.

News of an impending anti-Al Qaeda campaign in Mosul first surfaced in January, but Iraqi forces have since erected checkpoints on major roads leading to and from the city.

Al-Maliki's trip to Mosul, 225 miles northwest of Baghdad, is a repeat of a trip he made in late March to the southern city of Basra, where government troops fought radical Shiite militias to a standstill. That fighting later spread to Sadr City.

Mosul is considered the last important urban staging ground for Al Qaeda in Iraq after the terror group lost its strongholds in Baghdad and other areas in central Iraq during the U.S. troop buildup last year.