At the time, Princes William and Harry expressed their disgust by issuing a strongly-worded statement appealing to other media organisations not to follow suit.

They said: “As her sons, we would be failing in our duty if we did not protect her as she once did us. Therefore we appeal to all forms of media throughout the world to appreciate fully that publishing such material causes great hurt to us, our father, our mother’s family and all those who so loved and respected her.”

This latest breach is bound to anger them as they organise her memorial pop concert for July.

The documentary, called Diana: The Witnesses in The Tunnel, claims to shed light on the confused moments after the  crash in which Diana and Dodi Al Fayed were both killed on August 31 1997.

But critics claim that the pictures add nothing to the debate and are yet another attempt by Channel 4, whose chief executive is  Andy Duncan, to generate publicity through controversy. News of the latest row comes  days after the station was ordered to apologise to viewers over the Celebrity Big Brother race scandal.

More than 45,000 viewers complained to the regulator Ofcom after the channel failed to curb racist bullying of Indian actress Shilpa Shetty in the show.

Diana’s former private secretary, Patrick Jephson, said yesterday that he was “profoundly shocked” and disgusted by the decision to show the pictures.

Lord St John of Fawsley, a close friend of Diana and founder of Sky TV, described Channel 4’s move as shameful. He said: “I think it is terrible and they should be thoroughly ashamed of themselves. They certainly shouldn’t be subsidised publicly to follow up such causes.”

The co-founder of the Diana Appreciation Society, Alan Berry,  said: “This is not only deeply offensive, distressing and insulting to her two sons, but also to the millions around the world who loved her and care about her memory.”

The documentary makers claim the pictures will help to dispel myths about the aftermath of the crash – such as allegations that photographers hindered paramedics.

A Channel 4 spokesman said the programme, made by the station’s history department, presented the arguments in a considered, responsible and balanced fashion.

“The death of Diana Princess of Wales has been a defining moment in British contemporary history,” he said. “There is genuine public interest in examining how events unfolded in the hour or so immediately after the crash.

“Channel 4 has carefully and sensitively selected the pictures used in the programme. These photographs are an important and accurate eyewitness record of how events unfolded after the crash.

“We acknowledge there is great public sensitivity surrounding pictures of the victims, and those have not been included. In none of the pictures is it possible to identify Diana or any of the victims.

“Only one image 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.We are confident that when people have seen this film they will agree it is a well-made and responsible documentary.”

A Clarence House spokesman said the princes will not comment – but added: “Princes William and Harry have made their position clear in the past about the publication of pictures of this nature.”