A wave of attacks across Iraq, including more than a dozen car bombs, killed at least 28 people on Sunday while the head of Baghdad's provincial council escaped assassination.

The violence was the latest in months of unrelenting bloodshed, the country's worst since 2008, that has sparked concern Iraq is slipping back into the all-out sectarian war years earlier that killed tens of thousands.

Authorities have implemented tough restrictions on movement in the capital and elsewhere, and carried out wide-ranging operations against militants, but militants have pressed their attacks across the country.

On Sunday, at least 14 car bombs struck 11 towns and cities across Iraq, leaving 28 dead and more than 101 wounded.

The deadliest violence struck in and around the city of Hilla, the predominantly Shiite capital of Babil province south of Baghdad, where four car bombs killed 16 people, according to police and medics.

"I saw many people with burns, and people who were on fire, they were screaming for help," said Sajjad al-Amari, a 22-year-old witness to one of the car bombings, on the outskirts of Hilla.

Another witness, Karrar Ahmed, told AFP he saw "many shop owners who were thrown to the floor, many were killed and wounded, and they were lying on the ground, among the goods from their shops."

Ahmed, who was shaking with nerves, said incompetence on the part of the security forces had "cleared the way for terrorists to target, and kill, civilians."

No group immediately claimed responsibility for the violence, which largely struck majority Shiite Muslim areas of the country. Sunni militants linked to Al-Qaeda, however, often target Iraq's Shiite majority, whom they regard as apostates.

In Baghdad, meanwhile, a car bomb hit the convoy of Riyadh al-Adhadh, the chief of the provincial council and a Sunni lawmaker belonging to the party of the national parliament speaker.

Adhadh was unharmed but two others, including one of his bodyguards, were killed and four were wounded.

The blast shattered the windows of nearby shops and buildings, and security forces imposed a cordon around the scene in the aftermath of the attack, according to an AFP journalist at the scene.

Another car bombing at a market on the outskirts of the southern port city of Basra killed three people and wounded 15 others, officials said.

Several other attacks south of Baghdad -- in Karbala, Nasiriyah, Kut, Suweirah and Hafriyah -- as well as the predominantly Sunni cities of Abu Ghraib, Baquba and Mosul left seven others dead.

The latest bloodshed comes amid a months-long increase in violence, which has left more than 4,000 dead already this year, as the country grapples with a prolonged political deadlock and spillover from the civil war in neighbouring Syria.

Just a day earlier, a suicide bomber at a funeral near Mosul, Iraq's main northern city, killed 27 people and wounded dozens more, while violence in just the past week has left more than 150 people dead.

Authorities insist a weeks-long campaign targeting militants is yielding results, claiming to have captured hundreds of alleged fighters and killed dozens more, with security forces apparently having dismantled several insurgent training camps and bomb-making sites.

But the government has faced criticism for not doing more to defuse anger in the Sunni Arab community over alleged ill-treatment at the hands of the Shiite-led authorities.

Analysts and diplomats say militant groups have exploited that on the ground 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.