Chief Executive John Lee on Saturday said safeguarding national security is fundamental for a strong and stable Hong Kong.

Speaking at a national security legal forum in Wan Chai, Lee said national security loopholes were addressed after Basic Law Article 23 legislation took effect in March.

"From the anti-national education movement in 2012, Occupy Central in 2014, the Mong Kok unrest in 2016, to the 2019 social unrest and the Hong Kong version of a 'colour revolution', they used large-scale riots to create unrest," he said.

"Thanks to the central government, decisive action was taken to implement the National Security Law in Hong Kong. It addressed the legal vacuum surrounding national security, it improved the electoral system, and implemented the principle of patriots governing Hong Kong. The city has finally returned to normality."

The Secretary for Justice Paul Lam said some countries had attempted to ruin Hong Kong's unique role in the nation's development.

"History tells us that we cannot afford to disregard national security risks. Indeed, security and development have a symbiotic relationship: one cannot exist without the other, and one will benefit the other. This is sheer logic and common sense," Lam said.

"Our national security law based on the principles of the rule of law provides high-standard security to guarantee and safeguard the better and sustainable development of Hong Kong in the long run."

The one-day forum is taking place at the Hong Kong Convention and Exhibition Centre.