The British government is expected announce the terms of an independent inquiry tomorrow into claims British soldiers murdered and mutilated Iraqi civilians and tortured nine others after a battle in southern Iraq in May 2004.
British defence secretary Bob Ainsworth will also name the person who will chair the investigation, although the date for the inquiry will remain undecided, a defence ministry spokesman confirmed.
A military police inquiry had found "no credible evidence" for the claims but defence ministry agreed in July to hold the inquiry after months of legal argument.
Lawyers for five Iraqis who say they were repeatedly beaten after being bound and blindfolded in the incident at a military facility in Maysan province said Britain had "fundamentally failed" to investigate the allegations.
Britain's Ministry of Defence says soldiers brought the bodies of 20 Iraqis back to a base called Camp Abu Naji for identification, together with nine Iraqi prisoners, after a battle at a vehicle checkpoint known as "Danny Boy" in Maysan province.
It says it released the 20 bodies the next day and that the prisoners were unharmed.
"We have found no credible evidence that those detained, as a result of the attack on British troops and prolonged fire fight at the Danny Boy checkpoint, were mistreated," the ministry said.
However, lawyers for the Iraqis said families of a number of the deceased Iraqis had claimed their relatives were alive at the time they were taken to the facility and were murdered there.
Phil Shiner, of Public Interest Lawyers, also representing the uncle of one of the dead Iraqis, said the inquiry had had to be "dragged out" from the British government.
He said emails showed the nine survivors had been seen by a Red Cross doctor who had said their injuries were
consistent with being kicked on the ground.
"There is very credible evidence there was clear ill-treatment," Mr Shiner told Reuters.
It will be the latest in a series of reviews into British military conduct in Iraq since the 2003 invasion.
An inquiry is already under way into the death of an Iraqi civilian, Baha Mousa, who died in British custody in Basra in 2003 after sustaining 93 injuries.
Earlier this month the Ministry of Defence said it was investigating a separate catalogue of 33 allegations of abuse, including rape and torture.