A half-dozen car bombs went off in neighborhoods of Baghdad, killing at least 31 people and leaving dozens wounded, according to security and medical officials.

The blasts went off minutes apart at around 6:00 pm (1500 GMT), the latest in a trend of attacks timed to coincide with Baghdadis visiting cafes and other public areas during the evening.

No group immediately claimed responsibility but militants linked to Al-Qaeda frequently carry out coordinated attacks targeting Iraq's Muslims.

Nine other people were killed in attacks earlier the same day, officials said.

In the morning, gunmen entered the home of an Arab militiaman in south Baghdad and killed him, as well as his wife, two sons and a daughter.

That came a day after two sets of attacks that killed 12 people, including a coordinated assault involving two suicide bombers and a car bomb on the home of the militia's national chief in which he was wounded.

From late 2006 onwards, Sunni tribal militias, known as the Sahwa, turned against Al-Qaeda and sided with army troops, helping to turn the tide of Iraq's bloody insurgency.

But Takfiri militants view them as traitors and frequently target them.

Also on Tuesday, two men were shot dead outside their homes in south Baghdad, while a policeman was killed by a roadside bomb in northern city of Mosul.

Attacks have killed more than 3,800 people since the start of the year, according to an AFP tally.

Officials have vowed to press on with a campaign targeting militants that Prime Minister Nuri al-Maliki says has captured 800 alleged militants and killed dozens of others, as well as dismantling training camps and bomb-making sites.

NJF/NJF