Iraq is mired in its worst violence since 2008, with more than 5,500 people killed this year despite several major military operations and tightened security measures.
In the northern province of Nineveh, two separate roadside bombs targeting army patrols killed three soldiers and wounded four others.
In Mosul, a policeman and a militant were killed in a shootout at a checkpoint, and a policeman was shot dead in a separate incident, police and a doctor said.
A suicide bomber also detonated a vehicle rigged with explosives near a police checkpoint on the outskirts of Fallujah, killing three policemen and wounding three others, according to officials.
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Just north of Baghdad, the local head of an anti-Qaeda militia and his son were killed by gunmen, officials said.
From late-2006 onwards, Sunni tribal militias, known as the Sahwa, turned against their co-religionists in Al-Qaeda and sided with the US military, helping to turn the tide of Iraq's insurgency.
But Sunni militants view them as traitors and frequently target them.
Iraq's mounting unrest has coincided with demonstrations by Sunni Muslims against alleged ill-treatment at the hands of the Shiite-led government and security forces.
Violence so far this year has left more than 5,500 people dead, the country's worst bloodshed since 2008, when it was emerging from a sectarian war in which tens of thousands were killed.
In addition to major security problems, the government has failed to provide adequate basic services such as electricity and clean water, and corruption is widespread.