Thomas Keys - killed by Iraqi mob

Their worries will be aired on BBC One's current affairs programme Real Story.

Some families have criticised the Ministry of Defence for its handling of the investigation, but the ministry said it could not release information about the deaths "prematurely".

Among those interviewed are Reg Keys, whose son Thomas 20, was one of six military policemen gunned down in a police station.

Mr Keys, of Llanuwchllyn, near Bala, north Wales, said: "They let those six lads drive into that town lightly armed, with inadequate communications straight into the valley of death."

"Incompetence is the word to sum it up. Absolute incompetence." Reg Keys, father of a victim

An MoD spokeswoman said: "The premature release of any information may prejudice the outcome of any future proceedings that may result from the Royal Military Police's investigation.

"The RMP (Royal Military Police) fully understand the families' desire for an early conclusion but it is vital to ensure that the investigation is as thorough as possible," she added.

Families of the soldiers who died claim the investigation could last up to three years.

The men were killed as a crowd surrounded a police station at Al Majar Al-Kabir, near Basra, in June, seven weeks after the war ended.

The MoD says information cannot be released 'prematurely'

"Incompetence is the word to sum it up. Absolute incompetence," said Mr Keys.

He added: "There was Thomas and his five brave colleagues standing side by side trying to hold off a frenzied Iraqi mob armed with high velocity weapons, baying for their blood.

"But we believe these six lads held the crowd off for about 40 minutes and this overwhelming horde of Iraqis have just rushed into this station and mowed them down.

'Horrific'

"It is horrific to think my 20-year-old son has witnessed this and someone has stood over his body and finished my dear, darling son off.

"For parents to come to terms with this after all the trouble and hard work you put in to bring up your son, you hand him over to the Army, yes you accept it can be a hazardous occupation.

"But you hand your son over hoping they are going to be responsible, but I feel on this day the Army were irresponsible and I can't forgive them for that."

Tony Fisher's 41-year-old brother Sergeant Simon Hamilton-Jewell from Chessington, Surrey, died in the attack.

Mr Fisher was asked how confident he was that the Army report would be truthful.

"On a scale of one to ten, 0.5 because we, in three and a half months, have received virtually no information," he said.

He added: "What it will be is a cover-up. Because they don't like to admit mistakes."

The soldiers were members of the 156 Provo Company attached to 16 Air Assault Brigade, based in Colchester, Essex.

They were attempting to defend the police station after a confrontation in which locals complained about heavy-handed weapons searches conducted previously by troops and the use of plastic bullets.

It was reported that two days before they were attacked there was trouble in the region over weapons searches conducted by British paratroopers.

The other soldiers who died were Corporal Paul Long, 24, from Colchester, Corporal Simon Miller, 21, from Washington, Tyne & Wear, Corporal Russell Aston, 30, from Swadlincote, Derbyshire and Lance-Corporal Benjamin Hyde, 23, from Northallerton, Yorkshire.

Real Story will be shown on BBC One (not in Wales) on Monday at 1930 BST.