Dozens of people have died in attacks by militants on two villages in central Iraq, say officials.
Three Iraqi soldiers and 10 members of a local anti-al-Qaeda militia died in the first clash near Baghdad.
The fighters, who have been linked to al-Qaeda, attacked an army checkpoint and commandeered a vehicle in Hawr Rajab village, south of the capital.
In another attack east of Baquba, 19 militants and two civilians were killed, according to the police.
In the clash near Baghdad, fighters over-ran an Iraqi army position, killing three soldiers and wounding another three, said police.
They then stole a Humvee armoured vehicle, changed into Iraqi army uniforms and attacked the headquarters of the Hawr Rajab Awakening Council, according to police.
A number of local anti-al-Qaeda police units have flourished across Iraq after being organised by mainly Sunni tribal sheikhs.
The US-allied awakening councils have been credited with helping to significantly reduce violence.
The BBC's Jim Muir in Baghdad says Thursday's bloodshed underlines the fragility of security gains made in recent months following the deployment of an extra 30,000 US troops into Iraq.
But US military commanders have frequently warned that despite the lull in violence, militants were still very much in business and could strike back at any time, he adds.