A series of car bombs in Baghdad has killed dozens of people, hours after the UN secretary-general urged the Iraqi government to address the root causes of violence in the country.

The attacks on Monday included a car bomb attack in the mainly Shia district of Shaab, with reports of up to 21 people killed. In southern Baghdad, gunmen attacked a checkpoint, killing three policemen and wounding four others.

In a speech in the capital earlier, the UN chief Ban Ki-moon urged Iraqi leaders to address the "root causes" of violence.

The secretary-general told the Iraqi prime minister, Nouri Al-Maliki, that Iraqi leaders "should ensure that there is nobody left behind. There should be political cohesion" and "social cohesion, and political dialogue, inclusive dialogue".

"The security situation in Iraq is undoubtedly a source of great concern," citing violence in Anbar province between a nexus of local tribesmen, Iraqi police and soldiers, and al-Qaeda linked fighters from the Islamic State of Iraq and the Levant.

But the Iraqi prime minister said what was happening in Anbar had "no relation to Iraqi problems" and rejected Ban's calls for dialogue and inclusion.

"Dialogue with whom - with al-Qaeda? There is no dialogue with al-Qaeda, and the Iraqi national decision is to end Al-Qaeda," Maliki said, referring to the ISIL.

Bloodshed in Iraq has returned to its highest level in five years, a surge of violence partly fuelled by the war that began in Syria some months before US forces ended their nine-year occupation of Iraq in 2011. 

ISIL fighters have clashed repeatedly with Sunni tribesmen and local police for control of Anbar province, while car bombs continue to wreak havoc.

On Sunday, three people were killed and dozens injured in a car bomb attack targeting a football stadium in Tuz Khurmatu, 170km north of Baghdad.

Source: Reuters