At least 18 people were killed and 21 others wounded when a bombing attack struck a Sunni mosque in Iraq on Friday, police said.
A city official in Samarra says the blast during Friday prayers also wounded at least 15.
Violence between Sunnis and Shiite Muslims in Iraq has risen sharply in recent months. The attacks have raised fears of all-out sectarian warfare.
Earlier this week, car bombs ripped through Baghdad – part of a series of explosions across Iraq that left at least 31 dead.
The violence escalated after the pullout of U.S. troops in 2011.