In the northern town of Tuz Khurmatu, 175 kilometres (110 miles) north of Baghdad, two people -- a female judicial investigator and a police sergeant -- were shot dead as they left the town's court, a local police lieutenant colonel and a doctor at the nearby hospital said, speaking on condition of anonymity.

Also north of the capital, an anti-Qaeda militiaman was shot dead and another was wounded in a gun attack on a checkpoint in Samarra, according to a police officer and a doctor at the city's hospital.

Three other militiamen were wounded by a bombing targeting their car in the town of Baladruz, 75 kilometres (45 miles) north of Baghdad, security and medical officials said.

The fighters were all members of the Sahwa, or Awakening movement, a collection of Sunni tribal militias that began siding with US forces against Al-Qaeda from late 2006 onwards, helping turn the tide of Iraq's violent insurgency.

Wednesday's attacks came a day after violence north of Baghdad left eight people dead -- six soldiers, a police general and a teenager whose corpse was mutilated.

Violence in Iraq is down dramatically from its peaks from 2006 to 2008, but attacks remain common -- 278 people were killed in August, according to an AFP tally based on reports from security and medical officials.