Establishing a sound legal system and law enforcement mechanism to safeguard national security has become a "major issue" and "urgent mission" for the Hong Kong Special Administrative Region, said Zhang Xiaoming, director of the State Council's Hong Kong and Macao Affairs Office.

The protracted street violence and unrest in the SAR, now in its seventh month, abetted and instigated by foreign forces, has posed an unprecedented challenge to the implementation of "one country, two systems", he said in an article published in People's Daily on Wednesday.

This has made it more pressing and necessary to improve such a flawed system, said Zhang.

He blamed the absence of legislation for Article 23 of the Basic Law as a major reason for the growing separatist activities by radicals in Hong Kong in recent years.

Article 23 stipulates that the HKSAR shall enact laws on its own to prohibit any act of treason, secession, sedition, subversion against the Central People's Government, or theft of State secrets, to prohibit foreign political organizations or bodies from conducting political activities in the SAR, and to prohibit political organizations or bodies of Hong Kong from establishing ties with foreign political organizations or bodies.

Thus, safeguarding national security is a core requirement for the implementation of "one country, two systems", as well as the SAR government's constitutional obligations, Zhang stressed.

The Macao SAR enacted Article 23 of the Basic Law in 2009 — a decade after the city's return to the motherland. Last year. Macao set up a commission chaired by the chief executive to safeguard national security.

Zhang also said the central government's exercise of its authority over the two SARs, as empowered by the Constitution and the Basic Law, should be further institutionalized and regularized.

Zhang laid out 10 powers in his article in respect to the central government's authority over the SARs, including the right to appoint and remove the chief executive and principle officials, and that the central government can instruct the chief executive on affairs as stated in the Basic Law.

According to the Basic Law, the central government shall appoint the chief executive and principal officials of the SARs.

The mechanism and procedure of how the central government selects, appoints, supervises and removes the chief executive and these officials should be improved, Zhang said.

Past experience has proved "one country, two systems" to be the best policy for maintaining the long-term stability and prosperity of Hong Kong and Macao, while the innovative solution should undergo tests in practice and be continually improved, he added.