Earl Spencer claims King Charles said Diana would be "forgotten soon enough" in explosive memoir

Earl Spencer has accused King Charles of telling him Diana would be 'forgotten soon enough' just days after her death in a memoir that has drawn an unusually harsh response from the Palace.

In extracts from Swan Song: Diana, My Sister, published by the Daily Mail ahead of its release tomorrow, the Earl claims the King made the comment on a phone call in 1997.

He says it came after an argument about whether the boys, then 15 and 12, should walk behind their mother's coffin.

The book also claims the King sounded 'giddily elated' on the call just after learning of Diana's death and has said he cannot be sure of the King's thoughts as he made it an assumption based on his tone.

The book also claims that Diana told her father a month before the 1981 wedding that she couldn't marry a man who didn't love her and that he refused to let her walk away.

Spencer also accuses Charles of telling Diana the day before the wedding that he wasn't in love with her, which he says was told to him via a friend of Diana's.

A Palace spokesperson said that it does not comment on books by nature but that the King is aware that 'the pain of fraternal grief can cloud reason'.

Buckingham Palace has not commented on the specific accusations.

Spencer told the BBC's Laura Kuenssberg that he was 'telling the truth' and that the Palace had 'smudged' its response as opposed to denying his claims, and later called the response 'astonishingly provocative and below the belt'.

Penguin Random House has confirmed that the passages quoted by the Daily Mail are accurate. The full book has not yet been independently reviewed.