Prince Harry recounts in his new book how he was physically attacked by his older brother Prince William during an argument over his wife Meghan, according to an excerpt leaked days before the memoir's publication.

In the latest salvo in the brothers' bitter feud, Harry says the alleged incident came after the heir to the British throne called Meghan "difficult", "rude" and "abrasive".

Details of the row come as the British royal family braces for the publication on Tuesday of Harry's book "Spare".

The undignified spat in 2019 -- the year after Harry and Meghan married -- allegedly saw William tackle his younger brother to the ground as they continued to argue.

"He grabbed me by the collar, ripping my necklace, and he knocked me to the floor. I landed on the dog's bowl, which cracked under my back, the pieces cutting into me," The Guardian newspaper quoted Harry's book as saying.

Harry then told his older brother to leave. William looked "regretful, and apologised", Harry recalled, according to the left-leaning daily, which last year questioned the monarchy's role in modern Britain.

'Harold'

Quoting from the exchange between the two princes in the book, the report said William turned and called back: "You don’t need to tell Meg about this."

"You mean that you attacked me?" said Harry.

"I didn't attack you, Harold," William responded, seeming to use a nickname for his brother.

The revelation follows a string of other broadsides in the wake of Harry and Meghan's decision to quit royal duties in Britain in early 2020.

A year after starting their new life in California in 2020, the couple told US chat show host Oprah Winfrey that Buckingham Palace failed to help Meghan when she felt suicidal and accused an unidentified member of the royal family of racism.

And in a Netflix docuseries aired last month they blamed William's office for negative coverage, claiming it briefed the media against them.

Buckingham Palace has not made any public response to the claims, although Harry's late grandmother, Queen Elizabeth II, said about the racism allegations that "recollections may vary" and promised an investigation.

William also snapped at a reporter who asked about the claims: "We are very much not a racist family."

Britain is gearing up for the coronation of Harry's father, King Charles III, in May following the death of the queen last year.

Harry, 38, was asked in an ITV interview to be aired on Sunday evening if he will attend the event but he dodged the question.

"There's a lot that can happen between now and then," he said in a new clip released on Thursday.

"The ball is in their court. There's a lot to be discussed. And I really hope that they are willing to sit down and talk about it," he says.

Shared grief

Harry and William previously enjoyed a close relationship, in part forged by their shared grief over the loss of their mother, Princess Diana, who died in a car crash in Paris in 1997.

As young boys, the pair provided the enduring image from the funeral, walking behind Diana's coffin.

Asked by interviewer Tom Bradby, a friend of both brothers, if "William might say 'How could you do this to me... after everything we went through?'", Harry responds tersely that William would "probably say all sorts of different things".

The former British Army captain adds that he still believes in the monarchy although he does not know if he will play any part in its future.

Responding to a question about invading his own family's privacy, having railed against the media for doing the same thing, he says: "That would be the accusation from the people who don't understand or don't want to believe that my family have been briefing the press."

In excerpts released earlier, Harry said he wanted "a family, not an institution".

"I would like to get my father back. I would like to get my brother back," he said.