The former Duke of York, who is launching a bid to quash search warrants which led to his arrest, instructed lawyers after discovering officers had allegedly removed "private and confidential material unconnected to the criminal investigation", the Telegraph reported on Wednesday.
Andrew was arrested on his 66th birthday earlier this year on suspicion of misconduct in public office following allegations he shared sensitive information with Jeffrey Epstein during his time as the UK's trade envoy.
The King stripped his brother of both his right to be a prince and his dukedom in late 2025 over his association with the convicted sex offender.
Andrew has been granted permission to challenge whether Thames Valley Police acted lawfully over the searches relating to his arrest in February.
A judge at the Old Bailey issued warrants which allowed police to raid Andrew's residence on the Sandringham estate and his former Windsor home, Royal Lodge.
The former duke, who now lives on the King's private Sandringham estate in Norfolk, was interviewed under caution on February 19 before being released under investigation.
Police began their searches of the properties on the same day, with the force confirming on February 24 that they had ended.
On Monday, a judicial spokesperson confirmed a private hearing in Andrew's legal claim is due to take place on Thursday at the High Court.
Andrew has been warned not to use the King's private money to fund his legal action.
He receives an annual stipend - the amount of which has not been disclosed - provided by Charles from his private funds, but a palace source said it has been made clear that these monies should not be used to fund the judicial review.
It comes as a Bentley which once belonged to the former prince went up for sale at Yorkshire car dealership.
The racing green Bentley Flying Spur was driven by Andrew to his father's funeral in 2021 and to his granddaughter's christening the following year, the Times reported.
It once bore one of Andrew's distinctive "DOY" personalised numberplates and is now on sale for Stg124,975 ($A237,000).
According to the Times, the vehicle was previously sold to a specialist Bentley dealership in 2024 or 2025.
Andrew Mountbatten-Windsor and Thames Valley Police have been contacted for comment.
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