The attack comes as the U.S.-backed Iraqi military is promising to launch a major offensive in Diyala province aimed at taming the last major insurgent belt north of Baghdad. Baqubah is the province's capital.

The woman, who was shrouded in a traditional black Islamic robe, detonated her explosives belt about 8:30 p.m. as she approached a group of Awakening Council guards in the central New Baqubah area, a police officer said.

The officer, who read the police bombing report but spoke on condition of anonymity because he was not authorized to release the information, and witnesses said the local Awakening Council chief, Naaim al-Duliami, was killed along with seven of his bodyguards.

The U.S. military in northern Iraq said that troops were investigating the bombing and that it could not immediately confirm that the attacker was a woman.

The Sunni turn against al-Qaeda has been credited by the U.S. military as a key factor in driving down Iraq's violence to its lowest point in more than four years. Also cited are the U.S. troop buildup and a cease-fire declared by anti-U.S. cleric Muqtada al-Sadr for his Shiite militia.

Members of the U.S.-allied Sunni groups have frequently been targeted by al-Qaeda in Iraq and other insurgents seeking to derail the security gains.

Baqubah and other areas in Diyala have been hit by several bombings in recent months as Sunni insurgents show they retain the ability to cause casualties. Two suicide bombers attacked army recruits at a Baqubah military camp last week, killing at least 28 people and wounding 57.

Laying the groundwork for the expected new Diyala offensive, American soldiers have been searching caves and blowing up suspected hideouts believed used by al-Qaeda near the mountain town of Qara Tappah, about 50 miles northeast of Baqubah.

They also checked IDs of adult males in each house and detained some on suspicion of being al-Qaeda operatives as part of this week's sweep, "Operation Cat's Eye."

U.S. commanders have said they will assist Iraq's government in pursuing the Diyala offensive against militants who are trying to regroup in the area.

Insurgency Is Considered Far Weaker, U.S. Envoy Says

The insurgency that bedeviled U.S. forces for years and killed thousands of Iraqis and Americans has withered to the point where it is "not even much of a challenge anymore" to Iraq's future, Ambassador Ryan Crocker said yesterday in an interview.

Crocker would not rule out that Iraq could again descend into sectarian warfare in a contest for power and resources. But he expressed optimism that ordinary Iraqis, enjoying a new calm on their streets, will not allow it.

"You talk to people [Iraqis], and they just say: 'Never again. We almost destroyed ourselves,' " he said. "There is almost a

kind of embarrassment over it: 'How could we Iraqis do that?' "

Crocker did not assert the insurgency is dead, but he came close to casting it as having surrendered the initiative and lost its appeal.

"Under current circumstances, it's not

a threat and arguably not even much of a challenge anymore," Crocker said.

- Associated Press