Former royal butler Paul Burrell has told the BBC he would love to give Princes William and Harry a "piece of his mind" and said it was time for them to "grow up".
Mr Burrell's book is due out on Monday
He said the brothers, who had asked him to stop his revelations about their mother, were being used as "emotional cannons" in his row with Buckingham Palace.
He also said his book on Princess Diana, which comes out on Monday, would never have been published if the Royal Family had made "just one phone call" to him.
The book has been serialised by the Daily Mirror for more than a week, and has included sensational revelations about the princess's marriage, divorce, relationships and death.
Speaking about the accusation that he had betrayed Diana, he said: "I felt immediately that those boys were being manipulated and massaged by the system, by the palace, by the grey men in suits, by those people who did exactly the same to their mother."
Mr Burrell was speaking in an interview with Fiona Bruce, to be broadcast in BBC One's Real Story on Monday night.
"We have to grow up and get on with it and the boys now are adults. They're not children anymore and their mother will be talked about," he said.
A spokeswoman for Clarence House told Real Story: "The princess's sons have made a very strong statement. There is nothing further to add to that."
The former servant insisted his book was a tribute to the princess, and denied he was publishing it in revenge after the collapse last year of theft charges against him.
"It would have been a very different world if the telephone had rung and the boys had said 'Oh Paul, we're sorry we couldn't help you during your trial, we just couldn't, our hands were tied'.
"'Everything would have been fine again...
"Just one telephone call would have stopped it, one. Is that too much too ask - really? Having served the Royal Family for 21 years, is one telephone call too much? It's not."
It has been reported that Prince William wants a secret meeting with Mr Burrell, to persuade him not to reveal any more secrets.
But Mr Burrell hinted that a second book may be in the offing.
"I can't say to you that I'm not going to stand in the princess's corner, I'm not going to be there to say 'you're wrong'. I can't say that.
"I have no plans at this moment in time to write another book, but I don't know what the future holds, do I?"
The book's publisher Tom Weldon, of Penguin, told BBC News the princes had nothing to fear from the book.
"When Princes William and Harry read the book I think their view will change dramatically.
"This book presents an incredibly positive portrait of Princess Diana, the Queen and the Duke of Edinburgh. It's very, very sympathetic."
The book has already gone on sale in the US.
Kathy Weir of Borders bookshop in White Plains, New York, said it would probably be a good seller.
"I know where I was when I found out that Princess Diana was dead, I know a lot of other people do to.
"It's kind of like when Kennedy was shot, or Challenger exploded.
"People who are interested in tales of tragedy, personal tragedy, and there are a lot of people here who follow the Royal family. Those sort of people will buy the book."
Real Story: BBC One, Monday 27 October at 1930 GMT.