A truck bomb has exploded near a Shiite mosque, killing at least 55 people and wounding nearly 200 in northern Iraq.
The explosion is the deadliest since April 24 when back-to-back suicide bombings by women attackers killed 71 people outside a Shiite shrine in Baghdad.
Major General Jamal Tahir, the police chief of Kirkuk, said the truck bomb exploded just after noon in a town just outside the city. At least 170 people were wounded.
He added that an investigation has yet to determine if the attack involved a suicide bomber or a parked truck.
The explosion came hours after Prime Minister Nouri Maliki called the withdrawal of US troops from cities by the end of this month a "great victory" and promised it would go ahead as scheduled.
Officials have warned that insurgents are likely to stage more attacks in the wake of the withdrawal to try to undermine confidence.
American commanders have turned over control of a key base on the edge of Baghdad's main Shiite district of Sadr City.
The sprawling slum was a militia stronghold that saw fierce clashes until a ceasefire following a US-backed government crackdown.
The Iraqis also reopened Zaytoun Street, which had been part of the walled-off Green Zone that houses the US Embassy and the Iraqi government headquarters.
The Iraqis have begun removing some of the protective blast falls around the Green Zone - part of a campaign to restore a sense of normality as violence has waned.
