A London jury found the pair -- a retired Hong Kong policeman and a former UK Border Force official -- guilty of assisting a foreign intelligence service following a weeks-long trial.

The high-profile case exposed how ex-police superintendent Bill Yuen, 65, and 40-year-old Peter Wai conducted "shadow policing" operations on British soil targeting Hong Kong dissidents and exiled pro-democracy protesters.

"The activities carried out by these men, on behalf of China, are an infringement of our sovereignty and will never be tolerated," security minister Dan Jarvis said in a statement, within hours of the verdicts.

"We will continue to hold China to account and challenge them directly for actions which put the safety of people in our country at risk.

"That is why the Foreign Office will summon the Chinese Ambassador to make it clear activity like this was, and will always be, unacceptable on UK soil."

Wai was also convicted of misconduct in a public office after he searched the interior ministry's computer system for people of interest to Hong Kong authorities.

- Politicians, campaigners -

The jury at London's Old Bailey court, which deliberated for nearly 24 hours, was discharged after failing to reach verdicts on a further foreign interference charge against each defendant.

Prosecutors promptly announced they would not seek a retrial.

The duo were remanded into custody ahead of sentencing at a later date.

The Old Bailey heard how Wai had gathered intelligence on the orders of Yuen, who was a senior manager at the Hong Kong Economic Trade Office (HKETO), which represents Hong Kong's government in London.

As well as dissidents, the pair paid "special attention" to British politicians, including senior Conservative Iain Duncan Smith.

They undertook information gathering, surveillance and acts of deception, with one operation capturing photographs of prominent campaigner Nathan Law.

Their activities coincided with Hong Kong authorities publishing bounties of around pound100,000 ($136,000) for information helping to identify several UK-based activists, including Law, jurors heard.

Another protester told the jury how Wai had threatened him with arrest for confronting a Hong Kong diplomat in London.

Messages on Yuen's phone showed surveillance of Law began as early as 2021, the prosecution said.

- Strained ties -

The defendants' activities were exposed in May 2024 when police foiled an alleged bid to snatch a former Hong Kong resident from her flat in the northern county of Yorkshire, the court heard.

Wai, of Staines-upon-Thames, southwest of the capital -- who was known to associates as Fatboy -- and Yuen, of Hackney in east London, had both denied wrongdoing.

The case came in the wake of tens of thousands of people, including democracy activists wanted by Chinese authorities, moving to Britain since Hong Kong enacted a draconian National Security Law in mid-2020.

The sweeping law, which severely curtailed freedoms in the former British colony, contributed to years of strained ties, which soured further as London and Beijing exchanged accusations of spying.

Britain's current Labour government has sought to reset relations, but faced domestic opposition from some quarters, in particular after it approved contentious plans for a new Chinese mega-embassy in London.

In his statement, Jarvis said the case proved "the strength of the powers we have to protect us from hostile activity carried out by foreign states".

"These convictions should send a clear message -- there will be serious consequences for anyone who seeks to undermine our security," he added.