A suicide bomber has attacked an Iraqi army convoy in the northern city of Mosul, killing at least 22 soldiers and three civilians, according to police sources.

Another 16 people were injured in the Monday morning attack.

The bomber drove a vehicle packed with explosives up to a military convoy in the eastern Kokchali district of Mosul, 390km north of Baghdad, before blowing himself and his car up.

"A suicide bomber was following the convoy and when it stopped in the middle of the road, he detonated his vehicle right behind it," said a policeman at the scene who declined to be identified because he was not authorised to speak to the media.

It was not clear who was behind the blast, but suicide bombings are the hallmark of al-Qaeda.

A separate attack in western Mosul killed four policemen, police said.

The attacks are the latest in a campaign of violence across Iraq that has raised fears of a return to full-blown conflict in a country where Kurds, Shia and Sunni Muslims have yet to find a stable way of sharing power.

Nearly 600 people have been killed in attacks across Iraq so far this month, according to violence monitoring group Iraq Body Count.

That is still well below the height of bloodletting in 2006 and 2007, when the monthly death toll sometimes exceeded 3,000.

Source: Agencies