By Corinne Reilly and Laith Hammoudi | McClatchy Newspapers

BAGHDAD — A suicide bomber detonated his explosives vest in a crowd of militiamen waiting to collect their paychecks Saturday, killing at least nine and wounding dozens more near the Southern Iraqi town of Iskandariyah.

Police said the attacker set off his bomb around 11:30 a.m.

The militiamen he targeted are known as the Sons of Iraq. With the help local tribal leaders, the U.S. military launched the Sons of Iraq in 2007. Many of the militia's members are former insurgents who helped kill Americans until the U.S. began paying them two years ago to turn against violence and help root out al Qaeda in Iraq.

The Sons of Iraq program is credited with playing a major role in the steep reduction in violence across Iraq over the past year or so.

The site of Saturday’s explosion is in Babil province, about 40 miles south of Baghdad. Police there said the bomber was wearing a Sons of Iraq uniform when he attacked.

The bombing caps off a bloody week here.

On Monday a series of seven explosions killed dozens in Baghdad. Back-to-back bombings Tuesday and Wednesday in the capital’s Kadhemiyah district killed at least 15. And on Friday at least seven people, including five American soldiers, died in a massive suicide attack in the northern city of Mosul.

This week marked the sixth anniversary of the fall of Saddam Hussein's regime.

U.S. troops are scheduled to withdraw from Iraqi cities in less than two months and President Barack Obama has pledged to pull most Americans from the country altogether by the end of next summer. But the recent upswing in attacks has raised concerns about what might happen when the U.S departs.

Sons of Iraq members, and especially leaders of the militia, are often targeted with violence. Some view them as traitors for allying with the U.S.

And tensions between the mostly Sunni Muslim militia and Iraq's mostly Shiite Muslim government are running high.

The government vowed last year to take over paying the Sons of Iraq and absorb many of its estimated 100,000 members into the Iraqi Army and national police force. But those promises have largely fallen flat and distrust between the militiamen and the government has remained a problem.

Government officials have said they believe many insurgents have infiltrated the militia’s ranks. They’ve issued arrest warrants for some Sons of Iraq leaders, and the detention of one in Baghdad’s Fadhl neighborhood sparked street clashes between his men and the Iraqi Army late last month.

There is widespread worry that the distrust will push Sons of Iraq members back to the insurgency, which would only escalate violence further.

(Reilly reports for the Merced Sun-Star. Hammoudi is a McClatchy special correspondent.)

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