One resident said he saw many casualties in the street and several buildings had collapsed.

 

Kirkuk is just outside the borders of the largely autonomous Kurdistan region and its population is a volatile mix of Kurds, Turkmen and Sunni and Shia Arabs.

 

Iraqi security forces are frequently targeted by bombers seeking to undermine the US-backed Iraqi government.

 

Police in many areas of Kirkuk have also been infiltrated by militias, making them a target for rival armed groups.

 

Protests

 

Also on Wednesday, dozens of students demonstrated against twin bombings a day earlier at Baghdad's Mustansiriya university, which killed 70 people and wounded nearly 140.

 

Three days of mourning have been declared by the education ministry.

 

In all, at least 105 people were killed in bombings on Tuesday and a shooting in the capital on a day when the UN said more than 34,000 Iraqi civilians died in violence last year.

 

The UN said data from hospitals and morgues put the total civilian death toll for 2006 at 34,452.