Prince Andrew has revealed that he "ceased all contact" with a suspected Chinese spy after concerns were raised by the government.
Andrew met the individual through "official channels" with "nothing of a sensitive nature ever discussed", a statement from his office said.
The businessman – described as a "close confidant" of Andrew – lost an appeal over a decision to bar him from entering the UK on national security grounds.
The man, known only as H6, brought a case to the Special Immigration Appeals Commission (SIAC) after previous Home Secretary Suella Braverman said he should be excluded from the UK in March 2023.
Judges were told that in a briefing for the Home Secretary in July 2023, officials claimed H6 had been in a position to generate relationships between prominent UK figures and senior Chinese officials "that could be leveraged for political interference purposes".
He was allegedly so close to the royal family that he was invited to Prince Andrew's birthday party in 2020.
He was also told by an adviser to Andrew that he could act on his behalf when dealing with potential investors in China, a hearing was told.
A letter referencing the birthday party from the adviser was discovered on H6's devices when he was stopped at a port in November 2021.
The letter said: "I also hope that it is clear to you where you sit with my principal and indeed his family.
"You should never underestimate the strength of that relationship… Outside of his closest internal confidants, you sit at the very top of a tree that many, many people would like to be on."
Officials said that H6 had downplayed his relationship with the Chinese state, which combined with his relationship with Andrew, represented a threat to national security.
A statement from Andrew's office said: "The Duke of York followed advice from His Majesty's Government and ceased all contact with the individual after concerns were raised.
"The Duke met the individual through official channels with nothing of a sensitive nature ever discussed.
"He is unable to comment further on matters relating to national security."
In a 53-page ruling, Mr Justice Bourne, Judge Stephen Smith and Sir Stewart Eldon, dismissed H6's challenge.
They said Andrew could have been made "vulnerable" to the misuse of his influence.
"The applicant won a significant degree, one could say an unusual degree, of trust from a senior member of the Royal Family who was prepared to enter into business activities with him," they said.
"That occurred in a context where, as the contemporaneous documents record, the duke was under considerable pressure and could be expected to value the applicant's loyal support.
"It is obvious that the pressures on the duke could make him vulnerable to the misuse of that sort of influence.
"That does not mean that the Home Secretary could be expected to exclude from the UK any Chinese businessman who formed a commercial relationship with the duke or with any other member of the Royal Family."
The three judges said that H6 had enjoyed a private life in the UK, which had been described as the businessman's "second home".
They added: "He has settled status, a home and extensive business interests in the United Kingdom. He was regarded as a close confidant of the duke."
The judges continued to say the Home Secretary was "rationally entitled to decide" there was a potential to leverage the relationship, adding H6 was "not candid" about his links to the CCP.
They concluded: "In our judgment it was open to the SSHD to take a reasonably precautionary approach to the risk, and to take action rationally aimed at neutralising it so far as possible.
"Whilst excluding the applicant would not necessarily halt his activities, it would significantly hinder them.
"Cultivating relationships with prominent UK individuals would logically be much more difficult if no meetings could take place in the UK."
