Prince William has remained "fiercely loyal" to his father as his relationship with Prince Harry has worsened.

The claim was made by bestselling author Christopher Andersen in his new book titled "Brothers and Wives: Inside the Private Lives of William, Kate, Harry, and Meghan."

In it, Andersen alleged that Harry confronted William and Prince Charles about shocking comments concerning his future child’s skin color. And rather than defending  his younger brother, William stood by their father.

"There’s a lot of bad blood between them now," Andersen claimed to Fox News. "It’s really Charles and William versus Harry and Meghan. William is fiercely loyal to his father. He thinks his father is a great historical figure who has been underestimated. And he feels for his dad. They all love the queen, but when you’re maybe going to be king when you’re almost 80 years old, it’s a sad position to be in. So William has been by his father’s side."

PRINCE CHARLES, PRINCE WILLIAM TOLD PRINCE HARRY HE WAS 'OVERREACTING' ABOUT ARCHIE'S SKIN TONE REMARKS: BOOK

Prince William

Prince William, the Duke of Cambridge, has been "fiercely loyal" to his father Prince Charles, author Christopher Andersen told Fox News. (Getty Images)

"William is not returning Harry’s phone calls and hasn’t for months," he alleged. "Charles and Harry have not spoken at all."

Andersen alleged that Charles was the royal who speculated about Archie’s skin tone before he was born. The comment, he said, was made on the day that the announcement of Harry’s engagement to Meghan Markle, a biracial American actress, was made.

"I was able to track down the person in the royal family who was responsible for this comment and caused all this trouble," Andersen explained. "During their interview with Oprah Winfrey [in March], Harry and Meghan talked about a member of the royal family who commented how light or dark their child might be. They wouldn’t reveal who it was. Harry later said the comment didn’t come from the queen or Prince Philip. Well, I found that it was a very innocent comment made by Prince Charles."

‘He turned to Camilla and said, ‘I wonder what the kids are going to look like,’" he continued. "You know, hair color, eye color, complexion. It wasn’t racially motivated or anything. But the men in gray who run things behind the scenes at the palaces spun it into something more sinister sounding. Harry was upset and asked Charles and William what was going on. They told him, 'You’re overreacting, you’re being oversensitive. Let’s move on.’ And it just added fuel to the fire. There was a lot of tension already, and that just made it so much worse."

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Prince William and Prince Harry

Christopher Andersen alleged that Prince William and Prince Harry haven't spoken "in months." (Getty Images      )

Andersen claimed this was the only time that Charles made any comments about the skin tone of the Duke and Duchess of Sussex’s future children.

"William said this is not a racist family – I think he’s right," said Andersen. "But I also understand Harry and Meghan’s reaction because they weren’t hearing the truth. What they were hearing was something that was being stirred up by the people pulling the strings behind the scenes in an Oz-like fashion."

"We don’t know their names," he shared. "The public doesn’t know their names. But they run the show. Even the queen is sort of at their mercy. Princess Diana’s butler, Paul Burrell, once took her aside and whispered, ‘There are forces at work that we know nothing about.’ It’s a sad situation, but it’s being created by the people that Diana called the ‘men in gray.’"

Andersen said that since Harry and Markle, 40, made the revelation to Winfrey, 67, in March, Charles, 73, has been "furious."

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Prince Charles

Prince Charles is allegedly "furious" after Prince Harry and Meghan Markle spoke to Oprah Winfrey in a televised interview that was watched by nearly 50 million people globally. (Getty          )

"Charles is furious at the situation he and the queen have been put in," said Andersen. "Her husband has died. There’s the pandemic and Brexit is still a problem. She needed everybody to be together. She needed all hands on deck. And instead, she gets this chaos that’s been handed to her by ‘Megxit.’"

Andersen said he "really doubts" that Harry’s relationship with Charles will improve anytime soon. He pointed out that the British royals had plenty of opportunities to reconcile since the Duke and Duchess of Sussex announced they were stepping back as senior royals.

"After Prince Philip’s funeral [in April], they set up a meeting with the three of them - Harry, William and Charles - with nobody else around," said Andersen. "It did not go well. The next day, Harry got on a plane and left. For the unveiling of the Diana statue [in July], a similar thing happened [with William]. Even though they were grinning from ear to ear, they were walking with their backs to each other. The queen’s platinum jubilee, which is happening next year, might be their next chance."

In response, a spokesperson for Buckingham Palace told Fox News that "we never comment on these sort of books." A spokesperson for Kensington Palace, which represents the household of William, 39, and his wife Kate Middleton had "no comment." A spokesperson for Clarence House, which represents Charles and Camilla’s household didn’t immediately respond to Fox News’ request for comment. However, a spokesperson told The New York Post that "this is fiction and not worth further comment." A spokesperson for the Duke and Duchess and Sussex also didn’t immediately respond to Fox News’ request for comment.

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Prince Harry Meghan Markle Oprah Winfrey interview

This image provided by Harpo Productions shows Prince Harry, from left, and Meghan, The Duchess of Sussex, in conversation with Oprah Winfrey. (AP)

Andersen is sticking by the claims he made in his book.

"I have sources that I’ve been tending to for 50 years," said Andersen, who has previously written several books on the royal family.

Shortly after Harry and Markle’s bombshell interview, Buckingham Palace issued a 60-word statement on behalf of the queen, 95.

"The whole family is saddened to learn the full extent of how challenging the last few years have been for Harry and Meghan," the statement said.

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Meghan Markle Prince Harry

The Duke and Duchess of Sussex reside in California with their two children. (AP)

"The issues raised, particularly that of race, are concerning," the statement added. "While some recollections may vary, they are taken very seriously and will be addressed by the family privately. Harry, Meghan and Archie will always be much loved family members."

After announcing they were stepping back as senior royals in early 2020, the Duke and Duchess of Sussex moved to the coastal city Montecito, California with their firstborn. On June 4, the couple welcomed their second child, a daughter named Lilibet "Lili" Diana Mountbatten-Windsor. The name pays tribute to both the queen, whose family nickname is Lilibet and Harry's late mother.

The Associated Press contributed to this report.