Attacks in Iraq killed 31 people Thursday as 11 car bombs struck nationwide, the latest in a surge of violence that has sparked fears Iraq is slipping back into all-out sectarian war.

The bloodshed, in which more than 6,000 people have been killed this year, is the worst prolonged stretch of unrest since 2008 and comes just months before a general election, forcing Baghdad to appeal for international help in battling militants.

Although there have been no claims of responsibility for much of the unrest, officials see the hand of a resurgent Al-Qaeda emboldened by the civil war raging in neighbouring Syria.

Attacks struck across the country, from the northern hub of Mosul to Kut in the south. They cut down civilians as well as security forces in a wide variety of incidents targeting markets, bus stations, a funeral tent and the convoy of a top police official, security and medical sources said.

Babil province, south of Baghdad, suffered the lion's share of the car bombs, as a half-dozen struck provincial capital Hilla and nearby towns, killing six people and wounding dozens more.

Another vehicle rigged with explosives targeted Salaheddin provincial police chief Major General Juma al-Dulaimi.

It killed three civilians and wounded two others.

Dulaimi himself escaped unharmed from the blast in the provincial capital of Tikrit, hometown of now executed dictator Saddam Hussein.

A suicide car bombing at a police checkpoint near Samarra, also in Salaheddin, killed three police and wounded three more.

Two more car bombs in predominantly-Sunni Salaheddin and two others in Wasit, a mostly Shiite province south of Baghdad, killed three people and wounded 15.

Also in Salaheddin, militants who set up a fake checkpoint gunned down six people -- a senior official in Iraq's identity card department and his wife, two policemen and two other civilians.

Meanwhile in Baghdad, a roadside bomb targeting a patrol of Sahwa anti-Al-Qaeda-militiamen killed two people, one of them a Sahwa fighter, and two other bombs elsewhere in the capital killed four more.

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.

Sunni militants view them as traitors and frequently target them.

Also on Thursday, shootings in the northern city of Mosul killed four people, including two members of the Yazidi religious sect.

Violence worsened sharply after security forces stormed a Sunni protest camp in northern Iraq on April 23, sparking clashes in which dozens died.

The authorities have made some concessions aimed at placating the protesters and Sunnis in general, such as freeing prisoners and raising the salaries of Sahwa fighters, and have also trumpeted security operations targeting militants.

But diplomats, analysts and rights groups say the government is not doing enough to address disquiet among Sunnis over what they see as mistreatment at the hands of the Shiite-led authorities.

Thursday's attacks take to more than 600 the number of people killed this month, according to AFP figures based on security and medical sources.

On Wednesday, the UN Security Council condemned the recent violence and voiced support for government efforts to tackle the bloodshed.

"The members of the Security Council expressed their deep condolences to the families of the victims and reaffirmed their support for the people and the government of Iraq, and their commitment to Iraq's security," a statement said.

Prime Minister Nuri al-Maliki used a recent trip to Washington to push for greater intelligence sharing and the timely delivery of new weapons systems in a bid to combat militants.

France and Turkey have offered assistance.