Mountbatten-Windsor has consistently denied any wrongdoing linked to his association with Epstein.
The former Prince Andrew is not a working royal – so Buckingham Palace no longer speaks on his behalf and is not involved in his legal battle.
But a royal source said the King’s financial support for his brother should not be directed towards paying for the judicial review that Mountbatten-Windsor is seeking.
It’s not been disclosed how much the King gives to Mountbatten-Windsor, but the funding for his brother was part of the arrangement when the former Prince Andrew was moved from his previous home at Royal Lodge in Windsor.
This allowance for Mountbatten-Windsor is not from the Sovereign Grant, which is the £138m in public funding for the monarchy.
It is drawn from the King’s private money, which includes his income from the Duchy of Lancaster, private estates and his own investments and inheritances.
At the time of Mountbatten-Windsor’s arrest, the King said the “law must take its course”, and the Palace is now distancing itself from the former Duke of York’s legal pushback.
Mountbatten-Windsor’s lawyers are understood to be challenging Thames Valley Police and the Central Criminal Court over the lawfulness of warrants used for searches of Sandringham and Royal Lodge – in what has been Andrew’s first public response since his arrest earlier this year.
Thames Valley Police has confirmed it is “engaged in legal proceedings in relation to warrants previously obtained from the Central Criminal Court”.
It added: “As these legal proceedings are currently ongoing, it would be inappropriate for us to comment further.”
Mountbatten-Windsor, who lost his titles as a prince and Duke of York over his connections to the sex offender Jeffrey Epstein, wants a judicial review to consider the legality of the search warrants.
A court hearing on Thursday afternoon will be part of Mountbatten-Windsor’s bid to quash the warrants.