Hong Kong Chief Executive Carrie Lam Cheng Yuet-ngor said the special administration region's government will do its part to safeguard national interest by "fully cooperating" with the nation's top legislature's proposal of a national security law for Hong Kong.

Her pledge came on Friday, as the National People's Congress will deliberate a draft decision to add a national security law in the Annex III of the Basic Law of Hong Kong.

"Legislation on national security is undoubtedly within the purview of the central authorities. Just as it is in any other country in the world, it is the authority of the country to legislate on its own national security," Lam said.

"Safeguarding national sovereignty, security and development interests is the constitutional requirement of the HKSAR, the duty of the HKSAR Government, and also in the interest of all the Hong Kong residents," she added.

The resolution is expected to be put to a vote by members of the NPC next week.

According to Article 18 of the Basic Law, national law listed in the annex shall be applied by way of promulgation or local legislation.

The national security law will be enacted through promulgation, according to the draft decision on establishing and improving the legal system and enforcement mechanisms for the Hong Kong Special Administrative Region to safeguard national security.

In supporting the NPC's decision to close the legal loophole, Lam said it is difficult for the SAR to complete its own legislation for safeguarding national security in the foreseeable future, citing the "increasingly serious situation in relation to national security" and "the difficulty of the executive and legislative authorities of the HKSAR".

Lam was referring to the long-standing abeyance of Article 23 of the Basic Law, which stipulates Hong Kong shall enact its own national security legislation to prohibit any acts that endanger national security, such as sedition and subversion.

Concerns over national security were heightened in the community after the city endured prolonged and often violent protests since last June, which soon morphed into an anti-government movement.

The violence associated with the anti-government activities "prompted" the public to "have a deeper understanding on the importance of national security and urge the HKSAR Government to respond proactively", Lam said.

During the social unrest, "Some people begged for foreign governments to interfere with Hong Kong's affairs and even impose sanctions on Hong Kong," Lam said.

"This kind of behavior has crossed the baseline of 'one country', sabotaging the relationship between the Central People's Government and the HKSAR, threatening China's sovereignty and national security and challenging the authority of the central authorities and the Basic Law," Lam added.

These acts worried the political and business sector and the members of the public, Lam said.

But she affirmed the legislation will not affect the legitimate rights and freedoms enjoyed by Hong Kong residents under the law or the independent judicial power, including that of final adjudication, exercised by the judiciary in Hong Kong.

It only targets acts of secession, subverting state power and organizing and carrying out terrorist activities, as well as activities interfering with the HKSAR's internal affairs by foreign or external forces, she stressed.

"I deeply believe the national law to be enacted by the Standing Committee of the NPC will seek to practically and effectively prevent and curb acts and activities that seriously undermine national security," Lam said.