Prince William “lunged” at Prince Harry and “grabbed him twice” in a row over his bombshell interview with Oprah Winfrey.
The incident, which took place two years after Prince Harry's brother allegedly hurt him by knocking him to the floor, is described in his new autobiography, Spare, which is due to be released in days.
It allegedly took place in front of their father, now King Charles III, after the funeral of their grandfather, Prince Philip in April last year.
The row was said to have developed as the trio were discussing the interview Prince Harry and his wife Meghan gave to Winfrey a month earlier.
Prince Harry said he was trying to address bullying allegations against Meghan, but his family “weren’t listening”.
“I waved a hand, disgusted, but he lunged, grabbed my shirt. 'Listen to me, Harold,'" Prince Harry wrote in his book, according to an excerpt shared in The Sun.
“I pulled away, refused to meet his gaze. He forced me to look into his eyes. 'Listen to me, Harold, listen! I love you, Harold! I want you to be happy.'"
Prince Harry said he replied: “I love you too … but your stubbornness is extraordinary!”
The Duke of Sussex said he tried to pull away but his brother grabbed him again and “twisted him” so they could maintain eye contact.
He said Prince William told him: “Harold, you must listen to me! I just want you to be happy, Harold. I swear I swear on Mummy's life.”
The duke said: “He stopped. I stopped. Pa stopped. He'd gone there.
“He'd used the secret code, the universal password. Ever since we were boys those three words were to be used only in times of extreme crisis.”
Prince William reportedly said again: “I swear to you now on Mummy's life that I just want you to be happy”, as Prince Harry replied: “I really don't think you do.”
Prince Harry said his brother then hugged him and said: “I love you.”
Prince Harry's ghostwriter JR Moehringer - in pictures
During the Oprah Winfrey interview, Meghan said members of the UK royal family had conversations with Prince Harry expressing concerns about how dark their son Archie's skin would be ahead of his birth.
In a clip from ITV's interview with the duke, which will be shown on Sunday, Prince Harry speaks about seeing “the red mist” in his brother during an alleged confrontation in 2019.
He says Prince William knocked him to the floor during the incident at his flat in Nottingham Cottage, Kensington Palace.
“He wanted me to hit him back, but I chose not to,” he tells Tom Bradby.
“What was different here was the level of frustration, and I talk about the red mist that I had for so many years, and I saw this red mist in him.”
The duke writes of the confrontation in Spare — an extract of which was leaked by The Guardian on Thursday.
Prince Harry writes: “[William] 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.
“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.”
Buckingham Palace has so far refused to comment on the claims.
In the book, Prince Harry also describes the guilt and grief he felt as a child while walking outside Kensington Palace after his mother Diana’s death.
Prince William and Prince Harry through the years - in pictures
He said he cried only once during the period after his mother's death, and he and Prince William were unable to show any emotion when they met grieving members of the public.
“Everyone knows where they were and what they were doing the night my mother died,” he said in another clip to promote the ITV interview.
“I cried once, at the burial, and you know I go into detail about how strange it was and how actually there was some guilt that I felt, and I think William felt as well, by walking around the outside of Kensington Palace.”
In other revelations, the book claims:
- He took cocaine
- The prince killed 25 people in Afghanistan
- Prince Harry believes his brother is his “arch nemesis”
- Prince William called Meghan “difficult”, “rude” and “abrasive”
- The brothers call each other Willy and Harold
- Prince Harry and Prince William begged their father not to marry Camilla as they feared she would be a “wicked stepmother”
- Prince William and his wife, Kate, encouraged Prince Harry to wear the Nazi uniform to a party
- Prince Harry visited a psychic who told him his mother said he was living the life “she couldn’t” but “wanted” for him
- Prince Harry still wants reconciliation with his family
Harry: The Interview will be broadcast at 9pm GMT on ITV1 and ITVX on Sunday. Spare will be released on Tuesday.