New Delhi, June 19 -- A former U.K. border official and a retired Hong Kong police officer were given prison sentences on Thursday for spying on dissidents and critics of Beijing in Britain.

Border Force officer Peter Wai and Bill Yuen, a former superintendent in the Hong Kong Police, posed as police or intelligence officers to conduct surveillance and gather information about Hong Kong dissidents and pro-democracy supporters, prosecutors said.

Their targets included former Hong Kong lawmaker Nathan Law and activists they referred to as "cockroaches," as well as British politicians critical of China, according to the prosecutors.

A jury found the two Chinese-British nationals guilty last month of breaching the National Security Act by ...