The US general in charge of coalition forces in Iraq has ordered his commanders to conduct "values" training to reinforce moral and ethical standards of soldiers in the battlefield.

The order came as The Washington Post reported that a US military inquiry into the alleged cover-up of the killing of 24 civilians in the town of al-Haditha would conclude that some Marines officers gave false reports of what happened to their superiors - who then failed to check the information.

Citing an unidentified Army official, the newspaper said that Major General Eldon Bargewell was expected to deliver his report to the Pentagon by the end of this week after a three-month investigation and would call for changes in how US troops are trained for duty in Iraq.

But the official declined to say whether the report, which identifies multiple failures, would find that there had been a cover-up, as has been alleged by the Democratic Congressman John Murtha, a former Marine colonel.

Separately, the death of a pregnant Iraqi woman and her cousin kept the spotlight on the actions of the US military in Iraq. The woman was being taken to hospital in the city of Samarra to give birth but was shot dead after her car mistakenly took a road restricted to military traffic.

Even before General Bargewell's report is delivered to the Pengaton, the commander of Multinational Corps Iraq, Lieutenant General Peter Chiarelli, ordered the new ethics training.

He said in a statement that the training would emphasise "professional military values and the importance of disciplined, professional conduct in combat" as well as Iraqi cultural expectations.

"As military professionals, it is important that we take time to reflect on the values that separate us from our enemies," he said. "The challenge for us is to make sure the actions of a few do not tarnish the good work of the many."

The training will be conducted in units over the next 30 days and was aimed at reinforcing training service members received prior to their deployment, according to the statement.

"Of the nearly 150,000 Coalition Forces presently in Iraq, 99.9 per cent of them perform their jobs magnificently every day," General Chiarelli said. "They do their duty with honor under difficult circumstances. They exhibit sound judgment, honesty and integrity. They display patience, professionalism and restraint in the face of a treacherous enemy. And they do the right thing even when no one is watching."

But he added that "unfortunately, there are a few individuals who sometimes choose the wrong path."

The killings at al-Haditha, an insurgent hotspot north of Baghdad, happened after a Marine driver in a Humvee was killed in a roadside bomb attack. A member of the Marines unit accused of murdering the 24 unarmed Iraqis in a subsequent reprisal has said that his colleagues had become "blinded by hate".

The White House has said that the details of two separate military investigations into the killings - which could be the worst case of criminal misconduct by US troops since the invasion - would be made public. "If laws were broken, there will be punishment," said President Bush yesterday.

The Times has gathered witness accounts of the alleged massacre in Haditha. Iman Hassan, a ten-year-old Iraqi girl, described watching US Marines kill her mother, father, grandmother, grandfather, four-year-old cousin and two uncles.

Neighbours corroborated elements of her story and also described the murder of a second family, which included five children, the youngest of whom aged 2 and 3.

Details of an initial military investigation, undertaken in March and leaked to The New York Times, showed flaws in the Marine unit’s original claims that the Iraqi civilians killed in al-Haditha were the victims of a roadside bomb.

Citing death certificates, the report showed that all 24 victims, including seven women and three children, had been shot, most in the head and chest. The investigation also found that $38,000 (£20,000) had been paid by the Marines to families of 15 victims.

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