Secretary for Security Chris Tang on Friday warned of potential national security risks posed by certain individuals who frequently visited inmates, alleging that they attempted to instil hatred against the government.

Tang cited two people who paid more than 600 visits to 106 inmates jailed over the 2019 protests.

Citing newspaper reports, the minister said the visitors either tried to make political gains through the prison visits or earn money by selling daily necessities to inmates. He also said that they were jailed over the protests themselves and are still greatly resentful towards society.

Tang said there's no evidence for the moment these visits constituted a crime. "But this is something we have to look into. Is there anyone trying to instil hatred, trying to endanger national security through influencing the inmates?" he said.

On mainland scientist He Jiankui being revoked of his visa granted under the Top Talent Pass Scheme, Tang said the government will further improve the scheme if necessary.

Authorities this week began checking the criminal record of applicants.