It is understood that the appeal was decided at Balmoral, the Queen's Scottish estate, over the weekend.

William, aged 16, and 13-year-old Harry, who enrolled at Eton, on Wednesday, are concerned at the constant references to their mother and the "Diana industry" which has burgeoned in the past year.

Their words are addressed not only to the media - newspapers, magazines, television and radio - but also to commercial interests marketing Diana memorabilia, and to members of the public who continue to mourn the Princess.

The BBC's Nicholas Witchell reports on the Princes' request

The statement was made on Princes William and Harry's behalf by their father's press secretary, Sandy Henney.

Princes: "Comforted enormously by sympathy and support"

It said: "Throughout the last year, since the death of their mother, Prince William and Prince Harry have been comforted enormously by the public sympathy and support they have been given.

"It has meant a great deal to them and they have asked me to express their thanks once again to everyone.

The statement went on to say: "They have also asked me to say that they believe their mother would want people now to move on - because she would have known that constant reminders of her death can create nothing but pain to those she left behind.

The constant reminders are upsetting for the Princes

"They therefore hope, very much, that their mother and her memory will now finally be allowed to rest in peace."

Since the death of their mother on 31 August, 1997, barely a day has gone by when she has not been featured in the media.

Throughout the whole of last year, since the unprecedented public reaction to her death, the princess has remained as controversial and well-publicised as she was in life.

Her signature was put on "charity" packs of Flora margarine - and also on scratch cards.

In the states, 'Barbie'-style dolls were made in her likeness.

Her image possibly adorned more trinkets and memorabilia even, than during her life.

Although not in the same astonishing numbers as in the immediate aftermath of the fatal car crash, mourners still flocked to London and the princess's final resting place, Althorp, to pay their respects on the first anniversary of her death.

Many came from as far away as Australia, new Zealand and America to lay flowers, messages and toys outside her home of Kensington Palace and Buckingham Palace.

Thousands also visited Althorp, where she lies buried in an island grave, as her brother Earl Spencer threw the gates open to tourists - and earlier this year hosted a rock concert in the grounds.

The princes marked the anniversary of their mother's death in a brief, private church service with other members of the Royal Family at the Balmoral estate, in Scotland.