Prince William lost his temper after discovering bullying claims had been made against Meghan Markle by palace aides, a royal author reveals.
Historian Robert Lacey claimed the Duke of Cambridge was "instantly furious" when he found a "Dossier of Distress" that had been put together by Kensington Palace's head of communications Jason Knauf, according to the Sun.
In the new edition of his controversial book Battle of Brothers, Lacey alleges that royal staff felt "humiliated" by Meghan and Harry.
One aide recalls in the book, "I overheard a conversation between Harry and one of his top aides. Harry was screaming down the phone."
And Lacey goes on to claim that William was "appalled" by the bullying claims, which clarified for him that "Meghan was fundamentally hostile towards the royal system".
"Prince William went ballistic when he heard the 'dossier of distress' that Knauf had gathered," the book claims.
But it all came to a boiling point when Knauf, who worked for both the Cambridges and the Sussexes, sent an official email in late 2019 alleging that Meghan had bullied her staff.
Meghan has strongly denied the allegations, with a spokesperson for the Sussexes saying she has been the victim of a "calculated" smear campaign.
But when William first heard about the allegations, he instantly called Harry and the brothers had a "fierce and bitter showdown", Lacey writes.
The bullying claims are now being investigated by a third-party law firm brought in by Buckingham Palace.
Last month Knauf left his role at the Cambridges' Royal Foundation after seven years, citing "personal reasons".
The allegations come as Harry prepares to return to the UK and see his brother for the first time since their grandfather Prince Philip's funeral.
The princes will see each other at the unveiling of a statue dedicated to their mother Princess Diana on July 1.
Kate Middleton is expected once again to step in and act as a peacemaker between them on what would have been Diana's 60th birthday.