Members of President Saddam Hussein’s militias have worn replica British and US uniforms when firing on their fellow citizens in the hope of turning local people against coalition forces.

They have also dressed as civilians to stage mock surrenders before shooting at US soldiers, according to the claims that form a lengthening list of “dirty war” tactics that the Pentagon accuses Iraq of using.

US officials say they presume that such battlefield ruses to be are the work of the Fedayin militia who are fiercely loyal to Saddam.

President Bush said that such incidents revealed that Saddam’s regime had evil at its heart and promised that those responsible would face justice.

He said: “In the early stages of this war, the world is getting a closer view of the Iraqi regime and the evil at its heart. In the ranks of that regime are men whose idea of courage is to brutalise enemy prisoners. They wage attacks while posing as civilians. They use real civilians as human shields. They pretend to surrender, then fire upon those who show them mercy.

“This band of war criminals has been put on notice: the day of Iraq’s liberation will also be a day of justice.”

Donald Rumsfeld, the US Defence Secretary, has also accused Iraq of using ambulances to carry military instructions, and other officials have said that Iraqi fighters have opened fire while taking cover behind civilians. One official said that an Iraqi woman who waved to British forces from the outskirts of Basra was later found hanged.

Brigadier-General Vincent Brooks, of US Central Command, said that some Iraqi fighters had acted little differently from terrorists.

At Father Firas Primary School in Umm Qasr yesterday, British troops found 400 live hand grenades, and dozens of rifles and rocket- propelled grenades among piles of exercise books, broken desks and pupils’ paintings.

Royal Marines found weapons, ammunition and equipment that took three four-tonne lorries to carry away. When war broke out, Baath party officers in Umm Qasr immediately seized up to 30 schools to house their weapons and family members.

Even where reporters have been “embedded” in coalition units, however, most such claims have been impossible to verify immediately and become part of the propaganda war, although some US claims have been verified by the coalition forces.

At a hospital in al-Nasiriyah, a photographer accompanying US troops took pictures of stockpiles of rifles and a case of atropine injectors of the kind used to counteract chemical nerve agents.

According to US officials, 3,000 chemical suits were also found at the hospital, raising fears that Iraqi forces are prepared to use chemical or biological weapons. Also in the hospital compound was a T55 tank, indicating the extent to which Iraqi commanders were prepared to make use of human shields.

US forces also found gasmasks in trenches abandoned by retreating Iraqis.

American officials said yesterday that they were examining evidence that appeared to show that Marine engineers caught in an ambush at al- Nasiriyah on Saturday were killed as they tried to surrender. That was said to have happened in the same incident in which the first five US prisoners of war were captured.

Iraqi officials have levelled their own charges at the coalition forces, most of them to do with coalition-inflicted civilian casualties.

Mohammed Said al-Sahaf, the Iraqi Information Minister, said yesterday that US forces had killed or wounded 500 residents and destroyed 200 houses in al-Nasiriyah as they pushed across the Euphrates.

A separate dispute is under way about the treatment of prisoners of war. The Pentagon has already accused Baghdad of violating the Geneva convention by showing American PoWs on Iraqi television and filming them answering questions.

Civil rights agencies are also monitoring the conditions of Iraqi prisoners in US hands.Some have been pictured by news photographers, which is also a possible violation of the Geneva convention.

Times Recommends

• The Japanese Prime Minister is doomed: or is he?
• Brighton company 'involved in cyber attack'
• The art of survival: it’s all in the mind