Channel 4 stood firm last night over its decision to use photographs from the scene of the Diana, Princess of Wales, car crash in a documentary - despite pleas from Princes William and Harry.

The broadcaster rejected calls from the royal brothers to remove the controversial images from Diana: The Witnesses In The Tunnel, which is being aired tonight.

William and Harry's private secretary, Jamie Lowther-Pinkerton, wrote to the channel, appealing on their behalf.

The princes believe the use of the pictures is a "gross disrespect" to their mother's memory, Mr Lowther-Pinkerton said in the letter.

He added that the images would cause the princes "acute distress" and intruded on the "privacy and dignity of her last minutes".

In his letter to Hamish Mykura, the Channel 4 executive who commissioned the programme, he asked: "If it were your or my mother dying in that tunnel, would we want the scene broadcast to the nation? Indeed, would the nation so want it?"

In a new twist, Mr Mykura, head of history, science and religion, revealed that his own father died in a car crash.

He claimed he would not object to images of his father's dying moments being broadcast if it were in the public interest.

Mr Mykura said: "I lost a parent in a road accident so I am in no doubt about the pain that can cause."

His father, Dr Walter Mykura, a geologist, died in a road smash in Edinburgh in May 1988, aged 62. He left a wife, three sons and a daughter.

Julian Bellamy, head of Channel 4, confirmed the pictures would be used, despite the princes' request.

They include one of Diana receiving oxygen from a French doctor as she lies dying, but her face is obscured.

Mr Bellamy said: "We have weighed the princes' concerns against the legitimate public interest we believe there is in the subject of this documentary and in the still photography it includes."

He stressed it was not the channel's intention to cause William and Harry distress, and no images of the victims of the crash are shown.

Media watchdog Ofcom has received 17 complaints in the past week. But it is only within the regulator's powers to investigate after a programme is aired. After broadcast, if complaints are received, the programme could be investigated on the grounds of whether it broke rules on harm and offence to the viewer.