Op-ed-Doran-Zimbabwean spy “The activities carried out by these men, on behalf of China, are an infringement of our sovereignty and will never be tolerated," Jarvis said.
"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."
A spokesperson for the Chinese embassy in Britain said in a statement that it has lodged solemn representations with the British government and China will take necessary measures to firmly safeguard its interests.
"The facts of this case clearly show that this is nothing but a political move of abusing the law and manipulating the judicial process by the UK side," the spokesperson said.
"Its sole purpose is to embolden those anti-China elements who are hiding in the UK and bent on destabilising Hong Kong, and to smear the Chinese government and the Hong Kong SAR government."
Two men, including a British immigration officer, were found guilty in a London court on Thursday of spying on behalf of Hong Kong and ultimately China, targeting prominent pro-democracy dissidents now based in Britain.
Relations between Britain and China have been strained since a national security crackdown on sometimes violent pro-democracy protests in 2019 in Hong Kong, which was under British rule for 156 years before reverting to Chinese sovereignty almost three decades ago.
(Reporting by William James in London and Jessie Pang in Hong Kong; Editing by Alex Richardson and Kim Coghill)