At least 30 people were also killed or wounded in deadly clashes in Baghdad's Shiite slum district of Sadr City between Shiite militiamen and US-Iraqi forces who claimed to have captured a leading insurgent there.
Fears of sectarian bloodshed rose again as at least five mosques were attacked across the country - three of them Sunni - the day after a car bomb exploded next to a Shiite shrine in Kufa, south of Baghdad, that killed 12 Shiites, most of them Iranian pilgrims.
Imam 'killed': claims
Sunni MP Adnan al-Dulaimi's party claimed that a police commando force and sectarian militias had kidnapped and killed Sheikh Said Mohammed Taha al-Samarrai, imam of a mosque in the town of Mahmudiyah, south of Baghdad.
Sheikh Abdel Ghafur al-Sammarai, the head of the Sunni religious endowment authority, also said in his Friday sermon that another imam of a Baghdad mosque, Sheikh Alaa Mohammed Abbas al-Rikabi, had been kidnapped.
"Militias must be dismantled and the police force must be reconstructed otherwise they will burn down Baghdad and the fire will destroy everyone," warned Sheikh Samarrai.
At least nine people were killed and 59 wounded, 20 of them seriously, when a car bomb went off against worshippers coming out of a Shiite mosque in the village of Tal al-Banat near the town of Sinjar, west of the main northern city of Mosul.
Local police said the bombers parked the car close to the mosque and fled the area.
Two civilians were killed by a car bomb outside a Sunni mosque in west Baghdad while three others died one a mortar round exploded in front of a Sunni mosque in northern Baghdad during prayers.
In Baquba, northeast of Baghdad, a bomb outside a Sunni mosque killed one person and wounding four.
Another two Iraqis were killed and four policemen wounded in clashes between police and rebels when a Shiite mosque in Salman Pak southeast of Baghdad was attacked.
Meanwhile the US military said "an estimated 30-40 enemy fighters were killed or wounded" in gun battles between Shiite militiamen and US-advised Iraqi forces in Sadr City.
The military said a "high-level insurgent leader" behind attacks on Iraqi and US-led forces and four associates were captured.
Sources in the defense and interior ministries said the clashes between Iraqi forces and firebrand Shiite cleric Moqtada al-Sadr's Mehdi army left at least nine people dead and 30 wounded.
In other developments, Japan started withdrawing its troops from Iraq with the first batch of 38 soldiers of some 600 troops being flown to Kuwait from the southern province of Muthanna.
Japan ordered its troops to leave Iraq on June 20.