Chief Executive John Lee on Tuesday said the government will spare no effort in pursuing Agnes Chow, who is suspected of national security offences, for planning to jump bail.
Chow, who co-founded the now-defunct Demosisto party, is living in Canada and has indicated she will not report to Hong Kong police this month as per her bail requirements.
Speaking ahead of the weekly Exco meeting, Lee said fugitives such as Chow will be hunted for life unless they surrender.
"Now that she has claimed to plan to jump bail and abscond from Hong Kong, the police will do their utmost to pursue her, to arrest her. Fugitives will be pursued for life unless they turn themselves in," he told reporters.
"The fugitive's blatant disregard of police bail terms and abscond bail show that the fugitive is completely devoid of integrity. The attempt to put forward excuses and to deceive and win sympathy is a complete disgrace."
The CE said some Hongkongers still underestimate the threats posed by foreign forces to national security, adding that the pain of the 2019 protests must not be forgotten.