An “emotional” Prince William has reportedly ruled out any involvement with a documentary his estranged brother is said to be planning to mark the 30th anniversary of the death of their mother.

There have been multiple reports in the British media that Prince Harry has approached family and friends of the late Princess Diana about taking part in a film to mark next year’s milestone.

They include her brother, Earl Spencer, to whom Harry remains close.

The Duke of Sussex is said to want to honour Diana’s legacy “in the most meaningful way”. But he is apparently still deciding on the best way to honour the princess, who died in a Paris car crash in 1997, and nothing is finalised.

If Harry does make a film, the Prince of Wales won’t be involved, according to Britain’s Times. It said William had declined “several offers” to make or appear in documentary tributes to Diana.

The Times reports that William also wants to avoid a situation where he and Harry are “pitted against each other” during film-making.

The Prince and Princess of Wales made a surprise public appearance in West Yorkshire on Tuesday. Photo: AAP

Friends of William told the newspaper that next year’s anniversary was “a difficult situation for him”, and that he remained “really emotional” about his mother’s death.

One royal commentator went further, suggesting that if the Duke of Sussex did push ahead with a documentary about Princess Diana – after years of personal revelations about the royal family – he risked deepening the rift with his brother.

“Harry obviously has every right to mark the anniversary of his mother’s death in any way he sees fit. I’m sure the world would love to see another documentary about Diana, once the most famous woman in the world who remains an icon for many,” former BBC royal correspondent Jenny Bond told The Mirror newspaper on Tuesday (British time).

“If Harry does go ahead with a new film, William, I’m sure, will maintain the dignified silence he has kept through all the bitterness of the past few years, including about the incendiary claims in Earl Spencer’s book.

“But I’m afraid it would deepen the rift between the brothers — which is surely the exact opposite of what their mother would have wished. It could also make difficult viewing for [Buckingham] Palace, especially after Earl Spencer’s broadsides against King Charles and the palace machine.”

If Harry does make a film, it is expected to be produced through Archewell Productions, his production company with wife Meghan Markle. It has a first-look deal with Netflix.

Diana with sons Harry and William at a British amusement park in 1993. Photo: Getty

Nine years ago, Harry and William worked together on two documentaries about their mother for the 20th anniversary of her death.

At a Kensington Palace screening for Diana, Our Mother: Her Life and Legacy, William said he and Harry considered it their final public word on Diana.

“We won’t speak as openly about her again,” he said.

William reportedly he sees the 20th anniversary films as his “final catharsis”.

Indeed, any joint project for the 30th anniversary of their mother’s death appears even more unlikely given the brothers’ strained relationship.

Harry and William were last seen together at the August 2024 funeral of their uncle, Lord Robert Fellowes. They sat on opposite sides of the church aisle and reportedly did not speak.

Their last joint public outing was their father’s coronation in May 2023. They were seated separately inside Westminster Abbey, with the Duke of Sussex two rows behind his brother.

Harry left Britain almost immediately after the service to return to his family, then living in California.

Reports of a possible documentary also come amid revelations in Charles Spender’s book Swan Song, which was published last week. Among the explosive claims in the Earl’s book are that the then Prince of Wales was “giddy” in the immediate aftermath of Diana’s death.

Both Harry and William have avoided commenting on the book at recent public outings. William and wife Kate made a surprise appearance on Tuesday to support rugby league star Kevin Sinfield on a seven-day ultramarathon endurance challenge for motor neurone disease charities.

He is said to be furious about the book, considering it a personal betrayal. William is also reportedly tired of people making money from his mother’s memory.

“He has spent decades imploring those who continue to profit from Diana to let her rest in peace,” royal author Rebecca English said.

“Now he must add his own uncle to that list.”

Bond said the “spiteful and unnecessary” book only served to further traumatise the brothers.

“Do William and Harry really have to witness another blistering family row? Do they want to be made to relive the agony of their mother’s death? What good can that do?” she said.

Bond pointed to a statement released by the then teenage brothers a year after Diana’s death. It said reminders of the tragedy brought “nothing but pain” and that their mother would want people to move on.

“Earl Spencer has done precisely the opposite,” she said.

Spencer, who took his book tour to New York this week, maintains he told the brothers about the upcoming publication at “exactly the same time”.

“I can say that Harry is completely fine about it,” he said.

Spencer also discussed his relationship with the princes in an appearance on CNN on Monday (US time).

“It’s pretty consistent in that I’ve always just been an uncle,” he said. “I think when you lose someone in your family, and they have children, you sort of are there for them.

“But I’m very realistic. They’re men in their 40s now. I’m there if needed,” he said. “It’s public record that Harry came to stay with me with his family in July. So if I’m needed, I’m there, but I’m not in anyone’s way.”