A bomb has ripped through a crowd of Sunni worshippers coming out of a mosque in northern Iraq after prayers at the start of the Muslim holiday of Eid al-Adha, killing 12 people and wounding 24, a police official has said.

The bomb went off on Tuesday morning as worshippers were leaving the al-Qodus mosque in the city of Kirkuk, 180 miles (290km) north of Baghdad.

No one immediately claimed responsibility for the attack.

More than 5,000 people have been killed in Iraq since al-Qaida and other militants stepped up attacks following a deadly security crackdown on a Sunni protest camp in April.

Much of the violence in Iraq is the work of the local al-Qaida branch, a Sunni extremist group. While it is possible that Sunni insurgents could be carrying out mosque attacks, hoping to stoke sectarian hatred, Shia militias may also be behind such assaults.

The latest attack came despite tight security measures imposed by security forces to prevent attacks during the four-day Eid al-Adha celebrations.