Yang Tengbo, described in a ruling last week by the Special Immigration Appeals Commission (SIAC) as a "close confidant" of Andrew, the Duke of York, waived his right to anonymity on Monday so he could respond to the accusation.
"I have done nothing wrong or unlawful, and the concerns raised by the Home Office against me are ill-founded," he said in a statement released by his lawyer, referring to Britain's interior ministry.
"The widespread description of me as a 'spy' is entirely untrue."
The 50-year-old, who had previously been granted anonymity in the commission's proceedings, was removed from a flight from Beijing to London in February 2023 and told that Britain intended to ban him from the country.
This happened the following month on national security grounds.
Yang appealed against the ban at the Special Immigration Appeals Commission, which rejected his case in a written ruling last Thursday - the first time the reported relationship had come to light.
Britain's Home Office told Yang they had reason to believe he was "engaging, or had previously engaged, in covert and deceptive activity on behalf of the United Front Work Department (UFWD) which is an arm of the Chinese Communist Party (CCP) state apparatus", in a July 2023 letter quoted in SIAC's ruling.
The Home Office said it believed Yang was "likely to pose a threat to UK national security".
Yang's lawyer, Guy Vassall-Adams, told the High Court on Monday that his client had waived his right to anonymity to make a statement, and the judge, Martin Chamberlain, agreed.
On Friday Andrew, 64, a younger brother of King Charles III, issued a statement to the BBC and other media in which he said he had "ceased all contact" with the individual once concerns were raised.
"The duke met the individual through official channels, with nothing of a sensitive nature ever discussed," the statement said.
The ruling said evidence obtained from Yang's phone showed Andrew, 64, had authorised him to set up an international financial initiative to engage with potential partners and investors in China.
The ruling did not say what the fund was intended for.
A spokesperson at the Chinese Foreign Ministry said on Monday that China had always been open and above board and has never engaged in deception or interference.
The spokesperson added that the groundless speculation was "not worth refuting".
In a statement on its website, the Chinese embassy in London early on Tuesday urged "the UK side to immediately stop creating trouble, stop anti-China political manipulation, and stop undermining normal personnel exchanges between China and the UK."
Reuters contacted Andrew's office for further comment but did not receive an immediate response.
The prince, once a dashing naval officer who served in the military during the Falklands War with Argentina in the early 1980s, has now become a royal pariah over his friendship with the late US sex offender Jeffrey Epstein.
He was forced to step down from a roving UK trade ambassador role in 2011, before quitting all royal duties in 2019 and then being stripped of his military links and royal patronages in 2022 amid allegations of sexual misconduct which he has always denied.
British media have reported that Charles had cut off his allowance and wanted to oust the duke from his Royal Lodge home on the Windsor estate.
Court documents about Yang referred to one in 2021 listing talking points for a call between him and Andrew in which he wrote the duke was "in a desperate situation and will grab onto anything".
