Twin explosions have reportedly struck inside a Sunni mosque in Samarra, killing at least 18 people.
Mizhar Fleih, a municipal official in the city of Samarra, said the attack occurred around midday during Friday Prayers.
Hospital officials said at least 15 people were wounded.
Samarra, 95 kilometers north of Baghdad, is home to the Musab bin Omair Mosque, a revered Shi'ite shrine.
Iraq is weathering its worst bout of violence in half a decade.
Militants have carried out numerous attacks on both Sunni and Shi'ite mosques this year, raising fears of a return to the sectarian strife that peaked in 2006-07 and killed thousands of people.
The February 2006 bombing of a Shi'ite shrine in Samarra itself sparked that wave of violence.
Based on reporting by Reuters, AP, AFP, and dpa