Princes William and Harry have accused former royal butler Mr Paul Burrell of "a cold and overt betrayal" of their mother, the late Diana, Princess of Wales.
Their unprecedented statement came at the end of a week of claims in the Daily Mirror about Diana's trials and torments, heralding publication next week of Mr Burrell's book, A Royal Duty.
In direct repudiation of those claims Prince William, speaking also on his brother's behalf, said: "We cannot believe that Paul, who was entrusted with so much, could abuse his position in such a cold and overt betrayal."
Mr Burrell last night refused to apologise for writing his controversial book and said he was saddened by the princes' statement.
The statement added: "It is not only deeply painful for the two of us, but also for everyone else affected, and it would mortify our mother if she were alive today and, if we might say so, we feel we are more able to speak for our mother than Paul. We ask Paul please to bring these revelations to an end."
Those revelations have included the depth of Prince Phillip's disapproval of Prince Charles's affair with Ms Camilla Parker Bowles and the contents of a letter to Diana from her brother, Earl Spencer, urging her to seek help for her "mental problems".
However, most harrowing for the young princes, almost certainly, was Mr Burrell's release of a letter Diana allegedly wrote to him naming someone she believed was plotting to kill her in a road accident just 10 months before the Paris crash which claimed her life.
The Mirror did not name the person mentioned in the letter in which Diana described the period immediately following her divorce from Prince Charles as the "most dangerous" phase in her life. The unnamed person, she wrote, "is planning 'an accident' in my car, brake failure and serious head injury in order to make the path clear for Charles to marry."
Headlines proclaiming that Diana foresaw the circumstances of her own death revived conspiracy theories suggesting that she and Dodi al-Fayed were the victims of a plot executed by the British secret services with the knowledge of a senior member of the royal household.
In France the issue of Diana's death came before the courts as three photographers who took pictures of her and Dodi al-Fayed in their car just before their fatal 1997 crash went on trial in Paris yesterday for invasion of privacy. The case will hang on a recently established precedent in French law under which the interior of a car is deemed private.