A suicide bomber attacked a shiite place of worship, or Hussiniyah, in the northern Iraq city of Kirkuk on Thursday, killing 12 people, a senior police officer said.
The bomber tried to enter al-Zahraa Husseiniyah, where family members of victims from violence the day before were receiving condolences, but was prevented by police from doing so, and detonated an explosives-rigged belt near the entrance instead.
The blast also wounded 18 people, said the officer, who was present at the scene. A medical official confirmed that an attack had taken place, but did not give a toll.
Two car bombs and a roadside bomb killed 10 people and wounded 17 in Kirkuk on Wednesday.
Tensions are festering between the government of Prime Minister Nouri al-Maliki, a Shiite, and members of the Sunni minority who accuse authorities of targeting their community, including through wrongful detentions and accusations of involvement in terrorism.
Protests broke out in Sunni areas of Iraq almost five months ago.
While the government has made some concessions, such as freeing prisoners and raising the salaries of Sunni anti-al-Qaeda fighters, underlying issues have not been addressed.
Violence in Iraq has fallen from its peak, but attacks are still common, killing more than 200 people in each of the first four months of this year, including more than 460 in April, according to AFP figures.