Prince Andrew allegedly tried to prevent his older brother Charles from becoming king, a new royal biography has claimed.

According to "Camilla, Duchess of Cornwall: From Outcast to Queen Consort," an upcoming royal book from veteran journalist, royal commentator and biographer Angela Levin, the Duke of York allegedly campaigned against the new King Charles III taking up the throne, hoping Prince William would be crowned instead. International Business Times could not independently verify these claims.

Prince Andrew allegedly wanted his nephew to have the crown before he was 18 so that he could become Regent, according to an excerpt published by The Telegraph from Levin's new book on the life of Queen Consort Camilla.

The biographer claimed to have been told by a "senior insider," who was not named, that Prince Andrew "lobbied very hard with the hope that Charles would not become king when his mother died, and that William would wear the crown."

The book also cited the unnamed senior insider as saying that when Princess Diana was alive, she allegedly "plotted" with Prince Andrew, through her friendship with his now-ex-wife Sarah Ferguson, to "try to push Prince Charles aside so Prince Andrew could become Regent to Prince William, who was then a teenager."

"They were dark and strange times, where paranoia became reality, and this was a worry," the insider claimed, according to the excerpt.

Queen Elizabeth II, who is said to have a soft spot for her second son, found Prince Andrew's behavior to be "very, very negative and extremely unpleasant" and disagreed with his plan, the book claimed.

Levin claimed she was told that it was "one of the rare occasions" Prince Andrew "didn't get his way."

Prince Andrew was allegedly "very angry" that he "couldn't rule the country in some way," according to the book.

The same insider claimed to Levin that Prince Andrew tried to block Charles from marrying Camilla by being "poisonous, mean, unhelpful and very nasty" about her to Queen Elizabeth II. He allegedly told his mother that Camilla was not aristocratic enough and was untrustworthy.

After his alleged plan to block Charles from the kingship fell through, Prince Andrew allegedly "remained so hostile to Camilla's emergence and acceptance that it's doubtful it has ever been forgiven," the book claimed.

Charles immediately became king after Queen Elizabeth II died at the age of 96 on Sept. 8. Camilla, who was previously known as Duchess of Cornwall, became queen consort upon her husband's accession to the throne.

Meanwhile, Prince Harry and Prince Andrew could be removed from another official duty if King Charles pushes through with alleged plans to rewrite the law so that his official stand-ins, or Counsellors of State, are required to be working members of the royal family, The Telegraph reported.

Prince Andrew, Prince Harry and Princess Beatrice would be removed from their duties as Counsellors of State if that happens as they are not working royals.

"Camilla, Duchess of Cornwall: From Outcast to Queen Consort" will hit shelves on Sept. 29.