Prince Harry says Prince William physically attacked him in book Spare - report

Prince Harry alleges in his new book that he was attacked by his brother Prince William in 2019 with such force that he was "knocked to the floor", according to a report from The Guardian newspaper, which claims to have seen a copy of the highly-anticipated tell-all memoir.

Spare is due out next week and according to the UK newspaper, one section goes into detail about the ugly confrontation between the two brothers which saw them come to blows.

The conflict is said to have happened at Harry's London home at an unnamed time during 2019 and saw William calling Meghan "difficult", "rude" and "abrasive", which Harry said was a "parrot[ing of] the press narrative" about his American wife, Harry claims.

Harry then writes that William "grabbed me by the collar, ripping my necklace, and... knocked me to the floor".

Harry claims the incident resulted in a "visible injury to his back".

The Guardian reports the passage details how the row between the two escalated, with them "shouting over each other" before William tried to explain to his brother he was trying to help him.

"Are you serious? Help me? Sorry - is that what you call this? Helping me?" Harry wrote he had replied at the time.

But rather than calm the situation, Harry said his response angered his brother "who swore while stepping towards him" as they then went into the kitchen.

Harry reportedly wrote he gave his brother a glass of water and said: "Willy, I can't speak to you when you're like this."

"He set down the water, called me another name, then came at me. It all happened so fast. So very fast. He grabbed me by the collar, ripping my necklace, and he knocked me to the floor," Harry wrote, according to The Guardian.

"I landed on the dog's bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out.”

The book also details how William had urged Harry "to hit back, citing fights they had as children".

The Guardian reported Harry saying he refused to do so. William then left, Harry said, before returning "looking regretful, and apologised" before he urged him: "You don't need to tell Meg about this."

"'I didn't attack you, Harold'," William reportedly said.

Harry said he didn't immediately tell his wife about the incident - but did call his therapist right away. However, Meghan later noticed "scrapes and bruises" on his back, and Harry was forced to tell her of the attack.

Harry reportedly writes in the book she "wasn't that surprised, and wasn't all that angry".

"She was terribly sad."

The news of the extract will come as yet another blow to the brothers' relationship which has been seen as fractured for years now. It may also appear to be in contrast to Harry's comments earlier this week in which he said he was keen to reconcile with William and their father, King Charles III.

Those comments came from a teaser trailer for an interview with ITV's Tom Bradby in which Harry admitted William and Charles have "shown absolutely no willingness to reconcile", but insists he wants to "get my father back, I would like to have my brother back".

In addition, the 38-year-old referred to the tension with his brother and father following his and wife Meghan, Duchess of Sussex's decision to step down as senior members of the royal family in early 2020 and move to the US.

Prince Harry's memoir Spare releases globally on January 10.