Convoy targeted

Also on Monday, a suicide bomber attacked an Iraqi army convoy in the northern city of Mosul, killing at least 22 soldiers and three passers-by, police said.

The bomber drove a vehicle packed with explosives up to a military convoy in the eastern Kokchali district of Mosul, 390 km 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 road, he detonated his vehicle right behind it," said a policeman on Monday at the scene who declined to be identified because he was not authorized to speak to the media.

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

It was not clear who was behind the blasts, but suicide bombings are the hallmark of al-Qaida, which has been regrouping in Mosul, Iraq's third-largest city and capital of the Sunni-dominated Nineveh province.

Insurgent groups such as al-Qaida have found willing recruits among Iraq's Sunni minority, which resents Shiite domination since the US-led invasion that toppled Saddam Hussein in 2003.