Crowds cheered are they bodies of US contractors were torn apart

Their bodies were dismembered and put on display in the town, which has been the scene of clashes with US troops.

During Friday prayers the clerics told worshippers Islam prohibited such acts.

The warnings came as attacks continued in Iraq. Two more US soldiers and three Iraqi policemen have been killed in a 24-hour period.

Hacked to pieces

The four US contractors were ambushed and killed as they drove through Falluja on Wednesday.

The bodies were dragged from the wreckage of their cars and hacked to pieces. Two of them were hanged from a bridge.

Prophet Muhammad prohibited even the mutilation of a dead, mad dog Sheikh Khalid Ahmed Senior Falluja cleric

At one Falluja mosque on Friday Sheikh Fawzi Nameq told hundreds of worshippers: "Islam does not condone the mutilation of the bodies of the dead."

He said such acts brought "humiliation to the faithful".

Another Falluja cleric, Sheikh Hamid Saleh called the mutilations "childish behaviour committed by ignorants who don't know the meaning of life and death".

Senior cleric Sheikh Khalid Ahmed said Prophet Muhammad had "prohibited even the mutilation of a dead, mad dog".

However correspondents in Falluja say there was no condemnation of the killings themselves.

More violence

The US-appointed Iraqi Governing Council, for its part, has condemned the killings. The US has vowed to bring those responsible to justice.

Top US military spokesman Mark Kimmit said coalition forces would re-establish control of Falluja - but he said force could be avoided if town authorities arrested those who carried out the murders.

"If they were to deliver these people to the criminal justice system, we will come back in and start the rebuilding of Falluja. That is their choice," he said.

Meanwhile, the US military has announced the death of two more American soldiers serving in Iraq in the past 24 hours.

A soldier belonging to the Army's 1st Armoured Division was killed by a roadside bomb in the al-Mansour district of Baghdad early on Friday.

On Thursday a Marine was killed near Falluja.

At least 283 US soldiers have been killed in combat since President George W Bush declared major operations over in May.

In a separate incident on Thursday gunmen killed three Iraqi police officers in Baquba, north of Baghdad.

The attackers reportedly fired on two police cars guarding a road junction and threw a hand grenade at them.

Both Baquba and Falluja lie within the so-called Sunni triangle, a stronghold for insurgents fighting the US-led forces in Iraq.