Harriet Harman wants a meeting with senior Washington officials

It was unacceptable for relatives to be denied the chance to hear what had happened, Harriet Harman said.

Ms Harman told GMTV's Sunday programme she was seeking a meeting with senior Washington officials over the issue.

Her comments come after the coroner investigating British deaths in war zones expressed his frustration.

'Least we can do'

Ms Harman, one of the contenders for the Labour deputy leadership, told Sunday: "We need those American service people and experts to be in the coroner's court in order to give an account of the situation.

"We have an expectation they should come, so the bereaved relatives of the deceased servicemen can actually ask questions of what happened.

"When they do not come that is not acceptable and we are prepared to say that is not acceptable.

Combat operations are inherently dangerous US Department of Defense

"If our service people have died in Iraq the very least we can do is make sure there is a proper inquest, so their families can understand the truth of the situation of how their loved ones died."

Oxfordshire assistant deputy coroner Andrew Walker refused to read out statements by US soldiers involved in the death of ITN journalist Terry Lloyd after they failed to attend his inquest in October.

Delivering a verdict of "unlawful killing", he asked the attorney general to call for the unnamed marines to be extradited to the UK.

If our service people have died in Iraq the very least we can do is make sure there is a proper inquest Constitutional affairs minister Harriet Harman

Mr Lloyd, 50, was shot in the head by a marine while in a makeshift ambulance near the Shatt Al Basra Bridge on 22 March 2003.

His interpreter was also killed and his cameraman is still missing, presumed dead.

Mr Walker also criticised the US for failing to name or send witnesses to his inquest, also in October, into the deaths of two RAF men shot down by a US missile after completing a bombing raid on Baghdad in 2003.

Flight Lieutenant Williams, 35, and pilot Flight Lieutenant Kevin Main, from Staffordshire, were killed instantly.

Mr Walker found the deaths had been "entirely avoidable" and blamed a series of "glaring failures" that led the plane to be labelled as a hostile missile.

In a statement following the inquest into the death of Mr Lloyd, a spokesman for the US Department of Defense said an investigation in May 2003 had found US forces had followed the rules of engagement.

"The Department of Defense has never deliberately targeted non-combatants, including journalists," he said.

"It has been an unfortunate reality that journalists have died in Iraq. Combat operations are inherently dangerous."