The Iraqi interior minister has told the families of six military police officers murdered in 2003 he will try to bring their killers to justice.
The six officers had been helping to train police
In a letter seen by the BBC, he says the British soldiers were honourable men who came to liberate his country.
The Red Caps died after being attacked by an Iraqi mob near Basra.
John Miller, who lost son Simon, said the letter had given more comfort than anything from the UK government. The MoD said relatives did have support.
Mr Miller, whose son Cpl Miller was 21 when he was killed, was so frustrated by what he saw as the lack of support from the Ministry of Defence that he and two other parents decided to write to the Iraqi government last summer.
The reply sent to the relatives of the six dead men was received on Friday.
In the letter, Iraqi interior minister Jawad Bolani promises to "reach those criminals and bring them to justice".
The six officers had been helping to train police in the town of Majar al Kabir in southern Iraq.
A gun battle broke out on 24 June 2003 between local people and a unit from the parachute regiment.
Due to a communications failure, the paras withdrew, unaware they were leaving the Royal Military Police Officers behind - the Red Caps were then murdered by a mob.
Eight suspects were quickly identified but the British government said it was unable to detain them. Arrest warrants were issued in Baghdad two years ago.
Describing the letter, Mr Miller, from Ouston, Tyne and Wear, said: "There were words in there that said to us that Simon and his five comrades did not die in vain."
The five others who died were Sgt Simon Hamilton-Jewell, 41, of Chessington, Surrey; Cpl Paul Long, 24, of Tyne and Wear; L/Cpl Benjamin McGowan Hyde, 23, of Northallerton, North Yorkshire; L/Cpl Tom Keys, 20, of Bala, north Wales and Cpl Russell Aston, 30, of Swadlincote, Derbyshire.
An MoD spokesman said it had discussed the families' concerns on a number of occasions and routinely raised the issue with Iraqi officials.
It also continued to press for actions at the highest level to bring those responsible to justice, he said.
"We welcome the Iraqi Ministry of Interior's assurances to the families and will continue to support the families and the Iraqi government in pursuing this case, " he added.