with inputs from This is London

London, May 28: Channel 4 was accused yesterday of "trampling on Princess Diana's grave" after it defied appeals by her sons not to broadcast a photograph of their mother dying.

William and Harry are said to be devastated by the decision to show the picture of the princess slumped in the back of a black Mercedes a few minutes after it crashed in a Paris underpass.

A French doctor is shown trying to fit an oxygen mask to her face while a passing student is helping her bodyguard, Trevor Rees-Jones, who lies seriously injured in the front of the car.

Channel 4 insists it will broadcast the paparazzo photograph next week in a documentary about the princess's death, despite the worldwide outcry provoked when an Italian magazine first published it last year.

At the time, the young princes took the extraordinary step of issuing an emotional statement expressing their disgust at the decision and describing how it had caused them "great hurt". They said they felt "deeply saddened that such a low has been reached" and begged other media organisations not to reproduce the picture.

A Clarence House spokesman said: "They have made their position on this very clear. They want their mother to be allowed to rest in peace."

A royal source added: "They regard this picture as utterly distasteful. It is tantamount to trampling on her grave, and they are deeply saddened by any decision to show it."

Channel 4 will blank out the face of the dying princess, and the other occupants of the car, when it broadcasts the picture in Diana: The Witnesses in the Tunnel, on Wednesday, June 6.

The documentary includes interviews with photographers and other witnesses to the crash on August 31, 1997, which also killed Dodi Fayed and his chauffeur, Henri Paul.

It features pictures showing the exact positions of those surrounding the car during the minutes following the accident in the Pont de l'Alma underpass.

Another picture shows a line-up of the seven photographers who were detained by the French police on the night of the crash.

Channel 4 - which is airing the programme as part of the build-up to the tenth anniversary of the tragedy - insisted it had "carefully and sensitively" selected the pictures used in the documentary, including the one of Diana dying.

A spokesman said: "It has been said that in the aftermath of the crash photographers were swarming over the car, hindering people from getting to the occupants and giving them help.

The programme is part of the lead-up to the ten year anniversary of Princess Diana's death

"The photograph illustrates and makes clear that this was not the case. It is the only image in the documentary that shows the occupants of the car after the crash and it has been appropriately obscured to avoid any unwarranted intrusion into their privacy or that of their families."

He added that all the pictures to be broadcast were an "important and accurate eyewitness record of how the events unfolded after the crash".

But it was pointed out that the same point could have been made without actually displaying the photo.

Diana's close friend Rosa Monckton said: "It is macabre and intrusive. This is not going to demonstrate anything we don't know, so it can't possibly be in the public interest.

"I would like to know how the director of this programme would feel if it was his mother. Channel 4 should either cancel the documentary or at the very least cut the section showing the picture."

Former Diana Memorial Fund trustee Vivienne Parry described the decision as "intolerable". She said: "They wouldn't show a picture of anyone else dying, so why do Channel 4 think its acceptable to show a picture of the princess? Viewers should show their feelings by refusing to watch this documentary."

Conservative MP Ann Widdecombe said: "This will cause a great deal of completely unnecessary upset to her sons and to many others who knew and admired Diana.

"It also serves no purpose whatsoever. Occasionally showing a shocking picture can help bring an issue to people's attention, but not in this case as we all know how the princess died. It is just Channel 4 trying to push back the boundaries."

John Beyer of Mediawatch UK said: "Channel 4 seem to think that arousing controversy does them good, when in fact they are out of step with public opinion. It shows a disgraceful lack of respect for the princess and her relatives."

The broadcasting watchdog Ofcom said it had no powers to prevent the documentary being aired. A spokesman said: "It is up to the broadcaster to make the decision on whether to go ahead with a programme. Ofcom will launch an investigation only if there are complaints from viewers who found it offensive."

Philip Armstrong-Dampier, who produced the documentary for ITN Factual, told the Observer: "We got the access because we took a long time earning the trust of the people we to. Most of these people - particularly the photographers - have not spoken since that time ... partly because some of them were being pursued through the courts.

"Some of the pictures we used came from passers-by, others from the police dossier of the images seized at the time.

"I hope the film shows how the case against the photographers snowballed and how they have been tarred by it all."

The documentary brings more controversy for Channel 4 after broadcasting watchdogs last week ordered it to make grovelling apologies for its catastrophic handling of the Big Brother race row.

Chief executive Andy Duncan faced calls to quit after Ofcom found it guilty of "serious editorial misjudgment" by airing the racist insults made towards actress Shilpa Shetty.

Tory culture spokesman Hugo Swire said: "After a week when the editorial policy of Channel 4 has been under such scrutiny we would urge it to think again about broadcasting this documentary. We would expect more from a public service broadcaster than showing sensationalist material in this way.

"The best thing Channel 4 could do for the public and Diana's family is simply not screen this programme."