LONDON >> Prince Harry alleges in a much-anticipated new memoir that his brother Prince William lashed out and physically attacked him during a furious argument over the brothers’ deteriorating relationship, The Guardian reported today.

The newspaper said it obtained an advance copy of the book, “Spare,” due to be published next week.

It said Harry recounts a 2019 argument at his Kensington Palace home, in which he says William called Harry’s wife, the former actress Meghan Markle, “difficult,” “rude” and “abrasive.” Harry claims William grabbed his brother by the collar and ripped his necklace before knocking him down, the newspaper said.

“I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me,” the book is quoted as saying. “I lay there for a moment, dazed, then got to my feet and told him to get out.”

Harry says he had “scrapes and bruises” as a result of the tussle. William later apologized, the extract says.

Separately, celebrity website Page Six reported that the book alleges William and his now-wife Kate encouraged Harry to wear a Nazi uniform to a costume party in 2005. Harry has repeatedly apologized and called the decision one of the biggest mistakes of his life.

Neither Buckingham Palace, which represents King Charles III, nor William’s Kensington Palace office has commented on the claims.

The book, scheduled to be released Tuesday, is the latest in a string of public revelations and accusations by Harry and Meghan that have shaken Britain’s royal family,

Harry, 38, and the American actress married at Windsor Castle in May 2018. Less than two years later, the couple quit royal duties and moved to California, citing what they saw as the media’s racist treatment of Meghan, who is biracial, and a lack of support from the palace.

Since then they have presented their side of the story in an interview with Oprah Winfrey and a six-part Netflix documentary released last month, which recounted the couple’s bruising relationship with the U.K. media and estrangement from the royal family.

In the series, Harry claimed William screamed at him during a family meeting and accused palace officials of lying to protect his elder brother, who is now heir to the throne. Meghan, 41, talked about wanting to end her life as she struggled to cope with toxic press coverage.

Harry has recorded interviews with British broadcaster ITV and CBS in the United States to promote the book. Both are due to be broadcast Sunday.

In snippets released in advance, Harry told ITV that the royal household had cast him and Meghan as “villains” and “shown absolutely no willingness to reconcile.” He told CBS that the palace’s refusal to defend him and Meghan from attacks was a “betrayal.”

Palace officials have declined to comment on any of Meghan and Harry’s allegations.

The book also explains the reasons for its title, the Guardian said. It said Harry recounts the alleged words of his father to his mother, Princess Diana, on the day of his birth: “Wonderful! Now you’ve given me an heir and a spare — my work is done.”

While William was destined from birth to be king, Harry, who is fifth in line to the throne behind his brother and William’s three children, has often appeared to struggle with the more ambiguous role of “spare.” He spent a decade in the British Army — years he has described as his happiest — before taking up full-time royal duties in 2015.

Since his split from the royal family, he has launched a new career, with his wife, as a U.S.-based charity campaigner and media personality.

Asked by ITV’s Tom Bradby whether he will play a part in the British monarchy’s future, Harry said: “I don’t know.”