Iraqi police say a suicide bomber has killed nine people and wounded at least 10 others in the town of Khalis, north of Baghdad.
Authorities say the bomber detonated an explosives belt near a Shi'ite mosque after Friday prayers.
In other violence, U.S. military authorities say coalition forces killed six terrorists in two separate raids Friday.
Four terrorists died in a raid in the town of Thar Thar, after authorities said they received information that insurgents were building bombs in two buildings.
The military said two other terrorists were killed during a raid against al-Qaida forces in Baghdad. Authorities said the soldiers discovered a large weapons cache, including automatic weapons.
Earlier Friday, Iranian state-run television announced that two Iranian nationals who were detained by U.S. troops in Baghdad have been released.
The two were among several Iranians detained in Iraq last week, under suspicion of inciting attacks against Iraqi troops.
Iraqi officials say President Jalal Talabani invited two of the Iranians to the capital, and they said he was unhappy that U.S. forces detained them. Iranian television described the pair as diplomats.
Meanwhile, Britain said one of its soldiers was killed Thursday when a roadside bomb exploded near his armored vehicle while on patrol in the southern city of Basra.
Some information for this report was provided by AFP, AP and Reuters.