A suicide bomber killed at least 20 people inside a Shi'ite Muslim mosque in northern Iraq on Wednesday after detonating his explosives in the middle of a crowded funeral ceremony.
The attack on a sensitive religious target came as Shi'ite Prime Minister Nuri al-Maliki faces pressure from mass Sunni protests that are heightening fears the OPEC country risks sliding back into widespread sectarian confrontation.
"A suicide bomber at one mosque killed and wounded tens of people. We don't know who is behind this," Amin Aziz, deputy governor of Salahuddin province, told Reuters. "We don't have a clear toll yet."
Police, who were still rescuing victims from the bomb site, said at least 20 were killed and 35 more wounded in the attack on Tuz Khurmato, a religiously and ethnically mixed city 170 km (105 miles) north of the capital Baghdad.
A year after the last American troops left the country, Sunni Islamist insurgents tied to al Qaeda still carry out major bomb attacks to stir up the kind of Shi'ite-Sunni confrontation that killed thousands in 2006-2007.
Maliki, a Shi'ite, is struggling to calm weeks of protests by Sunni Muslims while his fragile government, split among the Shi'ite majority, Sunnis and ethnic Kurds, is deadlocked in a crisis over power sharing.