Police said four civilians and two policemen were killed and seven wounded when a bomber blew up his vehicle in front of a police patrol in Baghdad's Al-Gazalyia neighbourhood on Wednesday afternoon.
Two Iraqi soldiers and two civilians were killed in the town of Kashifa, 150km north of the capital when a joint US-Iraqi patrol was hit by a roadside bomb, police said.
One Iraqi traffic policeman was killed and seven people were wounded when a mortar shell slammed into a central Baghdad square, an Interior Ministry official said.
A second policeman was among those hurt.
Two oil security guards were killed by gunmen near the northern refinery town of Baiji, while a policeman was shot and killed in Kirkuk.
Four US soldiers were killed and six wounded in an attack on a patrol near the northern Iraqi town of Baiji.
Police in the town said two Humvee patrol vehicles and a larger armoured vehicle were wrecked and burnt out.
The US soldiers were on patrol
when attacked overnight
The US military said the attack happened at 11.30pm (1930 GMT) on Tuesday.
It gave no details of what kind of weapons were used.
But there has been a series of big roadside bomb attacks on US patrols in recent weeks that have destroyed armoured vehicles and cost many lives.
Just last week, 14 Marines were killed when a landmine flipped over an amphibious armoured vehicle near Haditha, west of Baghdad.
It was the deadliest such incident of the war.