Gunmen have kidnapped up to 10 members of a local volunteer security force in north-east Baghdad, Iraqi police say.
Adhamiya Awakening volunteers mourned their leader on Monday
The volunteers were at a checkpoint in Shaab district when gunmen drew up in several cars and took them away.
It is the latest in a number of attacks on the armed volunteer forces, known as Awakening Councils, which are backed by the Americans and oppose Al-Qaeda.
The military leader of another Awakening Council in Baghdad was killed in a bomb attack on Monday.
Meanwhile, the US military in Iraq said it had launched a major joint operation with Iraqi forces to build on a recent reduction in violence and to attack militant strongholds.
The operation, being conducted at division and brigade level, will cover the entire country, the military said. It has been named Operation Phantom Phoenix.
"Al-Qaeda in Iraq is attempting to regain strength and establish new support areas in northern Iraq," said US military spokesman Lt Col James Hutton.
He said the militant group, blamed for fomenting sectarian strife, had fled its former sanctuaries but remains a dangerous threat in Iraq.
Correspondents say US counter-insurgency operations in the second half of 2007 pushed al-Qaeda out of Baghdad and outlying towns and agricultural areas.
Its fighters are reported to have moved into Nineva and Salahuddin provinces north of Baghdad, and remain in the city of Baquba and areas south of Baghdad.
Operation Phantom Phoenix will combine military activity and economic and developmental components to improve essential service and local governance, the US military said.