Details of the proposed national security law for Hong Kong will be announced possibly as early as next month, with the law's drafting proceeding full steam ahead, said Ip Kwok-him, a Hong Kong deputy to the National People's Congress.

Ip, who's also a member of the Executive Council of the Hong Kong Special Administrative Region government, said many Hong Kong residents are happy that the central authorities have decided to enact a national security law to quell acts of separatism and safeguard stability in the SAR.

"Enacting a national security law for Hong Kong meets the expectations of Hong Kong residents," he said, citing a recent citywide signature campaign in which nearly 3 million residents pledged support for the legislation.

The decision to introduce a national security law for Hong Kong was made at the fourth plenary session of the 19th Central Committee of the Communist Party of China in October last year, Ip said.

The central government, he said, had been unnerved by the violent protests that erupted in Hong Kong in mid-2019, with separatists waving British and US flags on the streets and operating discreetly with the aim of toppling the SAR government.

"The opposition camp has repeatedly challenged the central government's bottom line, and threatened to block legislating a national security law under Article 23 of the Basic Law, forcing the central government to act," said Ip.

"The national security law is a must as Vice-Premier Han Zheng, the highest-ranking official in charge of Hong Kong and Macao affairs, has said no one should doubt the central authorities' resolve to protect national security in Hong Kong."

The announcement of the national security law for Hong Kong has dealt a thundering blow to the opposition and radical camps even before the law comes into effect, Ip said.

Jimmy Lai Chee-ying, the owner of Chinese-language newspaper Apple Daily who has been barred from leaving Hong Kong after being charged with participating in unauthorized assemblies and criminal intimidation, recently made his third attempt to have the travel restriction revoked.

Barrister and former Democratic Party chairman Martin Lee Chu-ming, who has also been charged with participating in last year's unauthorized protests, said he does not support Hong Kong independence and has disassociated himself from those inciting a revolution in Hong Kong.

"I hope what he (Lee) said is true and is from the bottom of his heart," said Ip, who has known Lee for many years.

Ip also took a swipe at US House of Representatives Speaker Nancy Pelosi, who has praised last year's Hong Kong protests as a "beautiful sight to behold".