China has accused Britain of false accusation, “wanton stigmatisation” and arbitrary arrests after the unexplained death of a man charged with illegally assisting Hong Kong’s foreign intelligence service.

China’s foreign ministry office in Hong Kong said in a statement on its website that it strongly condemned Britain for what it said were false accusations against Chinese citizens, infringing their lawful rights.

Britain’s acts were “a wanton stigmatisation of China and arbitrary arrests and prosecutions of Chinese citizens in the United Kingdom”, it said.

Tensions between Beijing and London have been rising over China’s sweeping national security crackdown since 2019 when sometimes violent pro-democracy protests swept Hong Kong, a former British colony that returned to Beijing’s control in 1997.

Matthew Trickett, 37, a former Royal Marine who worked as an immigration officer and private investigator, was found dead in a park in the west of London on Sunday.

He had been granted bail along with Chung Biu Yuen, 63, an office manager at the Hong Kong Economic and Trade Office in London, and Chi Leung Wai, 38, also known as Peter Wai, who works as a UK Border Force officer.