Former Chief Executive CY Leung is offering bounties of up to HK$1 million for anyone who provides clues that aid the arrest of "national security law offenders", or to those who have information on "anyone who has fled the city".
Leung, who is the vice chairman of Chinese People's Political Consultative Conference, wrote on Facebook on Tuesday that the money would come from the 803 fund.
The fund is linked to a website he set up last year offering rewards for anyone who provides information that leads to the arrest and prosecution of anti-government protesters.
The website has a link to a phone number which people can call to provide their national security tip-offs.
Earlier on Tuesday, Leung also posted screengrabs of the announcements by Joshua Wong, Nathan Law, and Agnes Chow that they have quit the pro-democracy group Demosisto, with Leung's caption saying "of the three, the smartest is Agnes Chow".
Chow had written in her post that she will stop doing international outreach and advocacy work.
In another post on the same day, Leung also referred to the trio as part a "party of scoundrels", including Martin Lee, Anson Chan, Hong Kong localism scholar Chin Wan and pro-independence activist Wayne Chan in his list.
Chan said on Facebook on Sunday that he had jumped bail and left Hong Kong.