The central government's Office for Safeguarding National Security in Hong Kong will "implement the city's national security law in an in-depth manner" together with the SAR, director Dong Jingwei said in his first blog post since taking office in July.

Writing in his blog on the office's website Sunday, Dong reiterated President Xi Jinping's point, made in a meeting celebrating the 25th anniversary of the handover last year, that the underlying goal of one country, two systems is to safeguard national sovereignty, security and development interests of the country.

"The central government has built a comprehensive legislative and enforcement mechanism for the SAR to safeguard national safety, introducing the law, which had provided a solid security guarantee for the long-term prosperity, and started a new era for one country, two systems," he said.

He said the great rejuvenation of the nation has entered an irreversible process, while Hong Kong has been transformed from chaos to order and is advancing from stability to prosperity but still faces risks and challenges in maintaining long-term prosperity.

Dong said the office will use Xi's thoughts on socialism with Chinese characteristics in the new era as guidance, uphold a holistic view of national security, and unwaveringly implement one country, two systems.

"[The office] will work with the committee for safeguarding national security of the HKSAR and relevant departments, to deeply implement the national security law in Hong Kong, combat all acts that endanger national security, and safeguard national sovereignty, security, and development interests of the country," he said.

Dong hoped various sectors of Hong Kong could support the work, strengthen the awareness, and "jointly build a solid dam" of safeguarding national security, to "promote a greater role for Hong Kong in building a great country and rejuvenation of the nation."

Dong was, from past government statements, previously deputy minister of state security. He succeeds Zheng Yanxiong, who was moved to the city's liaison office in January.

'In-depth enforcement' set for national security law