PRINCES William and Harry last night branded former Royal butler Paul Burrell a traitor to their mother.

Prince William, 21, issued an astonishing statement on behalf of both princes, labelling Burrell's sale of his story a ``cold and overt betrayal'' of Princess Diana.

Burrell, who once said he would never tell about his time with the late princess, has released a string of lurid revelations in recent days, trailing his new book.

The princes said their mother would have been ``mortified'' by his actions.

Last night, a spokesman for the princes said they were prepared to meet Burrell to put a halt to the disclosures, which include details of Diana's affairs and a letter which talked of how she feared being murdered.

Prince William said in the statement, released by Clarence House where they live with Prince Charles: ``We cannot believe that Paul, who was entrusted with so much, could abuse his position in such a cold and overt betrayal.

``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.

``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.''

A Clarence House spokeswoman said William's statement was aimed at drawing the line under Burrell's continuing allegations. She said: ``It's telling Paul Burrell that they've had enough.''

Much of Burrell's new book is based on letters sent by Diana and received by her.

He claims Prince Philip told Diana he and the Queen ``disapproved'' of the Prince of Wales's affair with Camilla Parker Bowles.

In a letter, he allegedly said: ``I cannot imagine anyone in their right mind leaving you for Camilla.''

Burrell also revealed details of a letter which Diana sent to him, telling of her fears for her safety.

She claimed a powerful figure, who has not been named, was planning to stage a car accident in which she would be killed.

The princes finally lost their patience when Burrell revealed yesterday that Diana had nine secret ``gentleman friends'' including a Hollywood star, a sports legend, a leading musician and a famous politician.

The others included men known as the favourite, the novelist, the lawyer, the billionaire and the entrepreneur.

The princess referred to, and graded, her suitors by using a racing ``trap'' system, according to Burrell,who added he would sometimes have to fob off the less-favoured suitors if Diana did not want to speak to them.

Burrell claimed: ``We called it the trap system as if the men were competitors on a racetrack. The occupant of trap one never changed.

``He remained in pole position in the princess's eyes.''

The extracts do not reveal the identity of the nine men.

But in a US television interview, Burrell claimed Diana was still in love with Pakistani heart surgeon Hasnat Khan when she died alongside her lover Dodi Fayed.

Burrell said Diana and the surgeonwere ``two very like-minded people, two people who wanted to go out into the world and help others'', but that eventually Khan had broken off their relationship.

He also insists that Diana had no intention of marrying Dodi Fayed and worried about his problems with drink, drugs and prostitutes.

He told ABC TV in America: ``I spoke to her the day before she died. I know that the princess would never marry Dodi. He may have wanted to, but he wasn't the one.''

Burrell writes in his book that Diana had told him of fears that a marriage proposal was imminent.

He said that Diana asked him: ``What do I do, Paul, if it's a ring? I need another marriage like I want a bad rash.''

Burrell, who was cleared of stealing Diana's belongings when his Old Bailey trial collapsed, also described a meeting he had with the Queen after Diana's death.

He claims she sympathised with his concerns at the behaviour of members of Diana's family, who shredded some of her letters and belongings.

THE PRINCES' STATEMENT -- We cannot believe that Paul, who was entrusted with so much, could abuse his position in such a cold and overt betrayal.

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.