A series of Baghdad car bombings mostly targeting Shiite neighbourhoods were the deadliest in a spate of attacks that killed 34 people in Iraq Tuesday, security and medical officials said.

The attacks were the latest in a surge of unrest that has left more than 4,200 people dead this year, the highest toll since 2008 when Iraq was emerging from a brutal sectarian war.

At least seven car bombs went off across Baghdad from around 5:00 pm (1400 GMT), when Iraqis are typically shopping or visiting cafes, killing 26 people, security and medical officials said.

The deadliest of the bombings hit the eastern neighbourhood of Zafraniyah, where at least six people were killed.

Earlier in the day, a provincial official was shot dead in the capital's northeast.

No group immediately claimed responsibility for the attacks, but Sunni militants linked to Al-Qaeda often use coordinated car bombings in a bid to target Iraq's Shiite majority, whose adherents they regard as apostates.

"The continuing car bomb wave phenomenon is increasing in volume," Jessica Lewis, an analyst at the Washington-based Institute for the Study of War, told AFP.

"Casualty levels seem to be getting bigger," she said, adding that targeting civilians helped the militant group gain publicity.

Violence in northern Iraq killed another seven people, all of them members of the security forces.

Near the main northern city of Mosul, gunmen ambushed a vehicle carrying unarmed policemen and raked it with machinegun fire, officials said.

Six policemen were killed in the attack and two seriously wounded.

A separate attack west of Mosul, a primarily Sunni Arab city that remains one of Iraq's least stable, left a soldier dead.

In Fallujah, a former insurgent bastion west of the capital, militants wearing explosive belts attacked a police station and traded fire with security forces.

Three of the bombers were killed when their explosives blew up while a fourth militant was shot by police, officials said, adding that 12 policemen were wounded, including two officers.

The latest violence took the death toll for September to more than 400, the sixth consecutive month to top that figure, according to an AFP tally.

Authorities insist a campaign targeting militants is yielding results with hundreds of suspects captured and dozens more killed.

They say security forces have also dismantled a number of insurgent training camps and bomb-making sites.

But the Shiite-led government has faced criticism for not doing more to defuse Sunni Arab anger over perceived ill-treatment.

Analysts and diplomats say militants have exploited the minority community's disenchantment to recruit new fighters and carry out attacks.

The surge in violence comes as the government grapples with a prolonged political stalemate, with no significant legislation passed since March 2010 parliamentary elections.