Britain’s former prince, Prince Andrew, was arrested on Thursday on suspicion of misconduct in public office during his tenure as a trade envoy, as UK police investigations linked to the Jeffrey Epstein files intensified.

In a development described as unprecedented in modern British history, the arrest marks a fresh setback for Andrew, who was marking his 66th birthday.

He was stripped of his royal titles last year and asked to vacate his former residence by his brother, King Charles III.

In a statement, Thames Valley Police said: “As part of the investigation, we have today (19/2) arrested a man in his sixties from Norfolk on suspicion of misconduct in public office.” In keeping with standard UK practice, the suspect was not named.

Several UK media outlets reported that a fleet of unmarked vehicles, believed to be police cars, arrived early on Thursday at the Sandringham estate in eastern England, where Andrew now resides.

Fresh revelations last week appeared to indicate that Andrew sent convicted US sex offender Jeffrey Epstein potentially confidential documents during his time as a UK trade envoy.

In a November 2010 email seen by AFP, Andrew appeared to share reports on Vietnam, Hong Kong, Shenzhen, and Singapore following an official visit to Asia.

The former royal, now known as Andrew Mountbatten-Windsor, reportedly also sent details of the trip — on which he was accompanied by Epstein’s business associates — along with information on investment opportunities months later.

Andrew was previously stripped of his titles after one of Epstein’s victims alleged she had been trafficked to have sex with him. He has consistently denied any wrongdoing in connection with Epstein.

King Charles has expressed concern over his brother’s conduct and last week issued an unprecedented statement indicating that Buckingham Palace was “ready to support” police inquiries.

Official guidance stipulates that trade envoys are bound by a duty of confidentiality concerning sensitive commercial or political information obtained during official visits, according to the BBC.

Andrew served as a British trade envoy for a decade from 2001.

At least nine separate UK police forces have confirmed they are assessing reports that appear to link him to Epstein.

Police in Surrey, in south-east England, said on Wednesday that they had become aware of a redacted report alleging “human trafficking and sexual assaults on a minor” between 1994 and 1996 in the village of Virginia Water.

The report formed part of the latest tranche of millions of files released by the US Department of Justice from its investigation into Epstein, who died in prison in 2019.

“After reviewing our systems using the limited information available to us, we found no evidence of these allegations being reported to Surrey Police,” the force said in a statement.

“We therefore encourage anyone with information in relation to these allegations to report this to us.”

The statement did not name any individuals.

However, it comes amid calls from high-profile figures, including former UK prime minister Gordon Brown, urging police to examine dozens of flights dating back decades that arrived at UK airports and were allegedly linked to Epstein.

Writing in the New Statesman magazine last week, Brown said he had been “told privately that the investigations related to the former Prince Andrew did not properly check vital evidence of flights”.

“I have asked the police to look at this as part of the new inquiry,” he wrote, adding that it appeared “the authorities never knew what was happening”.

London’s Metropolitan Police has also launched an investigation into the relationship between the UK’s former ambassador to Washington, Peter Mandelson, and the disgraced financier.