At least 64 people were killed Friday when suspected Shia militiamen attacked a Sunni mosque in Iraq's eastern province of Diyala, a media report said.
A bomber blew himself up and other gunmen fired fleeing worshippers during Friday prayers in a Sunni mosque in Baquba city, 120km from Baghdad, BBC reported.
The attack is seen as a blow to Iraqi government efforts to secure backing from Sunni groups in its battle against Islamic State (IS) jihadis.
Diyala province has seen heavy fighting in recent weeks between IS and Iraqi troops backed by Shia militiamen, the report said.
In a separate incident in the province, five people were killed and 12 others injured, all of them Shias, when three roadside bombs exploded in Himreen area in northern Diyala, a police source told Xinhua.
The security situation began to drastically deteriorate in Iraq since June 10 when bloody clashes broke out between Iraqi security forces and hundreds of militants of the Islamic State (IS) Sunni extremist organisation.
The IS took control of the country's northern city of Mosul and later seized swathes of territories after the Iraqi security forces abandoned their posts in Nineveh and other predominantly Sunni provinces.