LONDON -- Princes William and Harry harshly criticized former royal butler Paul Burrell on Friday for what they called a "cold and overt betrayal" of their mother in revelations about her private life.

In a statement unprecedented for its strength of feeling, 21-year-old William, who was also speaking on behalf of his younger brother, said Princess Diana would have been "mortified" at Burrell's actions if she were alive today.

Burrell has written about his years as the princess's butler, and excerpts have been carried all week in the Daily Mirror newspaper. One of Burrell's claims is that Diana -- who died in a 1997 car crash -- feared for her life and spoke of a plot to tamper with the brakes of her car.

In the statement released by Clarence House, where they live with their father, Prince Charles, the young princes asked Burrell to put an end to his disclosures about Princess Diana.

"We cannot believe that Paul, who was entrusted with so much, could abuse his position in such a cold and overt betrayal," the princes said.

"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," the princes said.

Burrell was a close confidant of the princess, who once called him "my rock."

Excerpts from his forthcoming book "A Royal Duty," carried in the Daily Mirror, have included quotations from letters in which she reportedly described her regrets about her divorce from Charles.

Burrell also revealed letters he said Diana had received from her brother, Earl Spencer, and her father-in-law, Prince Philip.

Philip's letter was quoted as saying he had "never dreamed" Charles would leave Diana for his companion Camilla Parker Bowles.

In excerpts published Friday, Burrell denied claims that Diana planned to marry her companion Dodi Fayed and was pregnant with his child at the time of the Aug. 31, 1997 crash in which both of them died.

The former butler said that Diana, after her divorce, had nine suitors, including a famous politician and an actor, but that she was not ready to marry again. He did not reveal the names of the suitors and said Diana was in love with Pakistani heart surgeon Hasnat Khan, who eventually broke off their relationship.

The royal family, reportedly angry over Burrell's revelations, asked for and received sections of the book from its publisher.

After the report that Diana had feared a plot to eliminate her, Dodi Fayed's father, Egyptian-born billionaire Mohammed Al Fayed -- who has long contended the crash was part of a murder plot -- urged a public inquiry into the crash. That was rejected by the British government. A coroner's inquest will be held once legal processes in France are completed.

In France, three photographers went on trial Friday for taking pictures at the scene of crash in a Paris tunnel, which also killed Diana and Fayed's driver, Henri Paul. The trial stems from a criminal complaint for invasion of privacy filed by Fayed's father.

Jacques Langevin, Christian Martinez and Fabrice Chassery were among the professional photographers who pursued Diana's Mercedes.

The three photographers face up to a year in prison and a fine of $53,000. The prosecutor asked that they get suspended prison terms. A verdict is expected to be set for a later date.

Photos taken at the site were confiscated and never published.

In 2002, France's highest court dropped manslaughter charges against the photographers. An investigation into the crash concluded that Paul had been drinking and was driving at high speed.