Iraq violence killed 35 people including 15 civilians on Tuesday, officials said, as authorities hailed arrests in a campaign aimed at curbing the country's worst unrest since 2008.

Prime Minister Nuri al-Maliki has vowed to press ahead with operations to try to stem the bloodshed, which has claimed more than 3,500 lives already this year.

But analysts and diplomats say Iraq is not tackling the root causes of the unrest.

On Tuesday, six car bombs south of the capital killed six civilians and a policeman and wounded 98 people.

Two car bombs hit a bus and taxi station in Amara. Two more hit near Hilla, while the others struck in Nasiriyah.

Another bomb struck a cafe in a village north of Baghdad, killing five people and wounding 15 others, the latest in a string of attacks to target cafes in recent weeks.

And two separate bombings at a livestock market and a police station north of Baghdad killed three people, including a policeman, and wounded nine others.

Gunmen also killed two senior police officers and a civilian in the country's north, while a magnetic "sticky bomb" exploded on a university employee's car, killing him.

And sixteen militants were killed north of the capital.

Nine died and four were wounded in an apparent dispute between two militant groups, when a bomb targeting a vehicle exploded south of the ethnically-divided northern oil hub of Kirkuk.

Security officials said the slain militants were Al-Qaeda loyalists and included one Kurd and a Turkmen.

They said the bombing was carried out by Sunni militant group Ansar al-Sunna, apparently in revenge for an earlier attack on relatives of their fighters.

Seven other militants were killed by security forces north of Baghdad in two separate clashes, officials said.

Security forces have mounted some of the biggest operations targeting militants since the withdrawal of US troops at the end of 2011.

A top general said security forces arrested 116 militants on Tuesday, including dozens of Al-Qaeda-linked fighters, destroyed six of their vehicles, two training camps and a site where car bombs were being made.

And authorities have hailed the arrest of scores more people in operations in recent weeks.

Violence has surged this year to levels not seen since Iraq was emerging from a brutal Sunni-Shiite sectarian conflict in 2008.

Analysts and diplomats link the increased bloodshed to anger among Iraq's Sunni Arab minority over their alleged ill-treatment at the hands of the Shiite-led authorities.

In addition to security problems, the government in Baghdad has failed to provide adequate basic services such as electricity and clean water, and corruption is widespread.

Political squabbling has paralysed the government, which has passed almost no major legislation in years.