Former justice secretary Elsie Leung said safeguarding national security is an on-going constitutional responsibility, and that Hong Kong can enact new laws if new circumstances arise.

In an interview published in the Ming Pao newspaper on Tuesday, Leung said the SAR's constitutional responsibility to protect national security is not limited to offences under proposed Basic Law Article 23 legislation.

Leung, who was the secretary for justice when the city introduced Article 23 legislation in 2003, said she doesn't think the current proposals are "harsher" than the version put forward 21 years ago, adding that the law needs to keep up with the times.

For example, she said concepts like economic security had not been taken into account back in 2003.

Leung also said there is a need to legislate against crimes of treason to prevent a repeat of the 2019 unrest.

On suggestions that the proposed legislation should be "prepared but not used", the former justice chief said laws must be enforced. She said Article 23 "is not simply there to scare people".