The UK foreign secretary, David Cameron, has called for the release of the British citizen Jimmy Lai, the pro-democracy newspaper publisher facing a “politically motivated prosecution” in a high-profile trial in Hong Kong. In a significant intervention, the former prime minister condemned the charges against Lai, 76, who faces a possible life sentence if convicted under a national security law that China imposed after the 2019 pro-democracy protests. Lai is charged with colluding with foreign forces to endanger national security and conspiring with others to publish seditious material. The trial is being watched closely around the world amid concerns about the growing influence of Beijing on Hong Kong, a former British colony. Cameron said: “Hong Kong’s national security law is a clear breach of the Sino-British joint declaration. Its continued existence and use is a demonstration of China breaking its international commitments. “It has damaged Hong Kong, with rights and freedoms significantly eroded. Arrests under the law have silenced opposition voices. “I am gravely concerned that anyone is facing prosecution under the national security law, and particularly concerned at the politically motivated prosecution of British national Jimmy Lai. “As a prominent and outspoken journalist and publisher, Jimmy Lai has been targeted in a clear attempt to stop the peaceful exercise of his rights to freedom of expression and association. “I urge the Chinese authorities to repeal the national security law and end the prosecution of all individuals charged under it. “I call on the Hong Kong authorities to end their prosecution and release Jimmy Lai.” Cameron made the pleas after Lai’s son Sebastien met the foreign secretary last week, saying he had “left the meeting feeling hopeful that the UK will shortly add its voice to calls for my dad’s immediate and unconditional release”. Lai founded Hong Kong’s now defunct Apple Daily newspaper but was arrested in 2020 during a crackdown on the city’s pro-democracy movement. His case has become a key issue, especially among Tory backbenchers pushing for a harder UK government line on China. Cameron’s appointment led to questions about whether he would be willing to take a tough stance on Beijing given the “golden era” of relations between China and the West during his premiership. Since becoming foreign secretary, however, he acknowledged that China has become “much more aggressive, much more assertive” in “‘wolf warrior’ diplomacy” since he left No 10.