Photo taken on Oct. 1, 2020 shows a poster on the national security law at Pui Kiu Primary School, Hong Kong. (Xinhua/Wu Xiaochu)

Regarding teachers who only have a partial understanding of freedom of speech and academic freedom in school, he said that such freedoms have a bottom line and must be bound by law.

"Hong Kong is indeed a very liberal place but promoting ideas such as separatism to children in school is by no means allowed in any country," he said.

Responding to widespread calls for judicial reform in Hong Kong, Leung said an objective, calm and comprehensive assessment of the judiciary's problems must be made before discussing reform.

Leung said Hong Kong's judicial system was once operated by the British behind closed doors. Some Hong Kong judges now lack a proper understanding of the dire international environment and the complexity of national security, he said.

Every Hong Kong resident, including judges, need adapt to the evolving situation and stay current as Hong Kong's national security issues have become increasingly prominent in recent years, he said.

Looking ahead, Leung said HKSAR's long-term prosperity relies on deeper integration with the overall national development strategies.

"I still believe that Hong Kong is the most effective 'super bridge' between the country and the world. It is not only a portal but also a platform."