And in an outward show of the escalating sectarian tensions, a firefight erupted between rival Shia and Sunni neighbourhoods in Baghdad on Friday after a car bomb killed two Iraqi soldiers in the Shia distrct of Kadhimiya.
Hoping to defuse tensions, Shia cleric Muqtada al-Sadr said he would mediate between the influential Iraqi Muslim body Association of Muslim Scholars (AMS) and the Badr Organisation, the military wing of the Supreme Council for Islamic Revolution in Iraq (Sciri).
The influential cleric met Iraq's newly appointed Sunni Defence Minister, Saadun al-Dulaimi, on Friday.
Sunnis have accused the Badr Organisation of being the militia responsible for the recent killing of several Sunnis, including three imams.
At the same time, leading Shia cleric Abd al-Aziz al-Hakim called for Iraqi leaders to unite against the violence.
"We must preserve unity and fight against any attempts at discord that aim to divide Iraqis," said al-Hakim, head of the Sciri, one of two dominant political parties in the United Iraqi Alliance that controls the new government.
"I call on all Iraqis not to give in to this. I call on all religious Sunni and Shia clerics to stand against violence aimed at them."
After the car bomb in Kadhimiya, US forces moved into the area backed by gunships that fired several rockets on the Adhamiya Sunni neighbourhood, which lies across the Tigris river.
Iraqi forces came under mortar round fire in the area of the car bomb and AFP correspondents witnessed exchanges of gunfire across the river.
Announcing the mosque closures and plans to hold a meeting of at least 1000 Sunni leaders on Saturday, Shaikh Ahmed Abd al-Ghafur al-Samarrai said in his sermon: "It is a peaceful protest against heinous crimes and it will be repeated if these attacks happen again."
A gunfight between Shia and
Sunni groups erupted in Baghdad
He added: "We must unite to create a leadership for the community."
The AMS also denounced the killing of Shaikh Muhammad al-Allaq, a representative of Shia religious leader Ayat Allah Ali al-Sistani.
Shia worshippers attending Friday prayers across Iraq wiped their feet on US and Israeli flags painted on the ground at the entrance of several mosques.
The images were painted in response to a call by al-Sadr, protesting against the alleged desecration of the Quran at the US detention camp in Guantanamo Bay.
Shia Muslims demonstrated
against the US in Baghdad
The flags appeared outside mosques in Baghdad, in the city of Najaf and in the southern city of Basra.
And about 2000 people, carrying copies of the Quran, marched in protest in Nasiriya, 375km south of Baghdad.
"Eight wounded people, four civilians and four police and soldiers, have been admitted to hospital," a doctor in Nasiriya said, after clashes erupted between demonstrators and security forces.
Medical and security sources said that in Saddam's hometown of Tikrit the bodies of five Iraqis had been found - adding to the scores recently found dumped in Baghdad streets.
Iraqi PM al-Jaafari is struggling
to restore order in the country
In a rocket attack on Friday on the infamous Abu Ghraib prison in west Baghdad, five Iraqi detainees were wounded, the US military said.
There were no casualties among US troops at the prison, where US military guards were photographed abusing and sexually humilitating Iraqi prisoners.