New Delhi, May 9 -- A U.K. border official and former Hong Kong police officer were convicted Thursday of spying for China by carrying out what prosecutors called "shadow policing" operations in Britain.

Peter Wai and Bill Yuen, both dual Chinese and British nationals, posed as legitimate police or intelligence officers to conduct surveillance and gather information about Hong Kong dissidents and pro-democracy supporters, prosecutors said.

A jury in the Central Criminal Court in London found them guilty on charges they violated the National Security Act by assisting a foreign spy service. Wai was also convicted of misconduct in a public office.

"These convictions send a clear message that transnational repression, foreign interference,...