The bodies of 24 Iraqi civilians killed in an alleged massacre by American Marines in the town of al-Haditha will be exhumed by US investigators for forensic tests, it emerged today.

The information may help teams to establish how the civilians died and details in the sequence of events after a roadside bomb exploded in the town, killing a Marine in November.

The Naval Criminal Investigative Service hopes to determine whether the shots were fired at close range, the calibre of bullets used and the angles of the shots, according to sources close to the investigation quoted in the Washington Post.

Nouri al-Maliki, the new Iraqi Prime Minister, has accused coalition forces of committing an "odious crime".

Leaks from an ongoing US probe suggest that the troops raided a house, killing 24 civilians - including women and children - in retaliation for the death of their popular colleague in the bomb attack.

The Iraqi Cabinet has demanded access to US investigative files and announced that it would conduct an independent inquiry into the alleged massacre which has further strained relations between the Government and the multinational forces.

Mr al-Maliki said that he only learnt details of the al-Haditha killings through media reports. The US is conducting a separate investigation into allegations that there was a subsequent cover-up with officers on the ground, who initially reported that the civilians had all died in the roadside bomb blast.

"I hope it [the US investigation] will be fair for the sake of the victims," Mr al-Maliki told reporters during a visit to a new Baghdad power plant today. He is due to meet General George Casey, the US commander in Iraq, later today to discuss the release of the reports.

President Bush has promised a thorough and independent investigation, pledging that any soldiers found guilty of wrongdoing would be punished.

The US is braced for further criticism of the behaviour of its personnel with military spokesmen announcing that three or four other probes into cases of US troops killing Iraqi citizens are ongoing.

In one of these, prosecutors are expected to charge seven Marines and a Navy corpsman with murder.

The eight men are being held at Camp Pendleton, California, over the killing of a man in Hamandiya on April 26. There are allegations of a subsequent attempt to make the dead man look like an insurgent by placing an AK-47 rifle near his body.

Meanwhile, further details were emerging of another incident in Ishaqi, north of Baghdad in March. US officials said at the time that a militant, two women and a child died when US troops became involved in a firefight after a tip-off that an al-Qaeda supporter was visiting a house in the town.

The BBC has obtained video which appears contradict this. The footage instead appears to back an Iraqi police report that US troops rounded up and shot 11 people - including four women and five children - in the head.

Mr al-Maliki - whose government is dependant on coalition troops to tackle sectarian feuding among southern Shias and a relentless Sunni-led insurgency in the west - said that reports of such behaviour had become commonplace.

The Prime Minister, who declared a one-month state of emergency in Basra yesterday, said that some troops had: "No respect for citizens, smashing civilian cars and killing on a suspicion or a hunch. It’s unacceptable."

Although he did not elaborate, the Prime Minister said that the conduct of coalition troops would be taken into consideration: "when we review the presence in Iraq of the multinational forces."

An aide said that the government would review the existing UN mandate for coalition forces before it expires in December. He said that it was no longer content to grant all-encompassing powers to conduct raids and arrests.

Salam al-Zubaie, the Deputy Prime Minister and one of the most powerful Sunni Arabs in the new Government, said: "The coalition forces must change their behaviour. Human blood should be sacred regardless of religion, party and nationality."

He acknowledged that it was unlikely that Iraqi officials would be able to force the extradition of any troops but he demanded that the US authorities hand over its own investigation files.

The US responded to the mounting accusations of misconduct among its troops by ordering all 150,000 to undergo a crash course in battlefield ethics within the next month.

The Republican US House Speaker Dennis Hastert, who is heading a visiting delegation to Iraq, said: "We are increasing our training to make sure those types of things don’t happen again. If ... it did happen it should never happen again."

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