An Iraqi official says a bomb planted near a Sunni mosque in northern Iraq has killed 12 worshippers after morning prayers on a major Muslim holiday.

Police Colonel Taha Salaheddin says the attack took place in Kirkuk on Tuesday. The bomb went off as worshippers were leaving the al-Qodus mosque after prayers for the start of the Eid al-Adha holiday.

Salaheddin said the bombing also wounded 24 people.

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

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

On Monday, UN envoy Nickolay Mladenov had called for unity in Iraq on the occasion of the holiday.

"On this Eid and at this crucial time, I would like to plead for unity and understanding among all the Iraqis and their political, religious, and civil leaders," Mladenov said in a statement.

"It is only through working together that the people of Iraq can stand up to the violence that is tearing society apart."

Almost nothing is safe from attack by militants, and violence has reached a level not seen since 2008, when the country was just emerging from a brutal sectarian conflict.

Violence worsened sharply after security forces stormed a Sunni anti-government protest camp in northern Iraq on April 23, sparking clashes in which dozens died.

The latest violence takes the number of people killed so far this month to more than 310, and to over 5,000 since the beginning of the year, according to AFP figures based on security and medical sources.

Source: Agencies