A suicide truck bomb killed at least 34 people leaving a mosque on Saturday, hours after prime minister Nuri Al-Maliki urged Iraqis not to lose faith if a US military pullback resulted in more insurgent attacks.

Almost all US soldiers will leave urban centres by June 30 under a security pact signed by Baghdad and Washington last year, and the whole force that invaded the country in 2003 must be gone by 2012.

"Don't lose heart if a breach of security occurs here or there," Maliki told leaders from the ethnic Turkmen community, reiterating a warning that insurgents were likely to try to take advantage of the U.S. pullback to launch more attacks.

Analysts warn there may also be a spike in violence by mainly Sunni Islamist insurgents, including al Qaeda, and other violent groups ahead of a parliamentary election next January.

Hours after Maliki spoke, a suicide bomber detonated a truck filled with explosives as worshippers left a Shi'ite Muslim mosque near the northern city of Kirkuk, a city contested by Arabs, Turkmen and Kurds and which sits over vast oil reserves.

Thirty-four people were killed, including women and children and about 150 civilians were wounded as dozens of clay homes in the area were flattened. Many people were feared trapped under the rubble, and the death toll was expected to rise.

There was chaos at Kirkuk's main Azadi Hospital, where ambulance sirens wailed as workers rushed blood-splattered civilians, including several children, into the wards.

Outside, security officials brandished assault rifles to stop traffic as pick-up trucks raced through the gates carrying more victims of the blast at the al-Rasul Mosque.-Reuters