The Chinese embassy in London has accused Britain of sheltering fugitives, while Hong Kong's chief executive says eight pro-democracy activists wanted for alleged national security offences would be "pursued for life."
John Lee told reporters that he was urging the eight to give themselves up, adding that otherwise they would spend their days in fear.
On Monday, the authorities in Hong Kong offered rewards for information leading to their arrests.
The British foreign secretary, James Cleverly, sharply criticised the move, saying his government would not tolerate attempts by China to silence individuals in the UK or overseas.
All eight activists left Hong Kong after Beijing imposed a sweeping national security law. Among them is one of the leaders of the 2019 protest movement, Finn Lau. He told Newsday of his concerns for his personal safety: “The risk of physical abduction or some kind of physical harassment escalates because of this bounty…It somehow encourages people, especially maybe some Chinese Communist Party Pinkies…that is…transnational repression.”