HONG KONG (Reuters) - A Chinese official admonished Hong Kong on Thursday for failing to introduce a national security law, ramping up pressure on the former British colony to enact the contentious Article 23 that critics say will further choke its freedoms.

FILE PHOTO: A general view of Victoria Harbour and downtown skyline is seen from the Peak in Hong Kong, China August 4, 2017. REUTERS/Bobby Yip//File Photo

The global financial hub has been ruled under a “one country, two systems” principle since it returned to China in 1997, guaranteeing freedoms not enjoyed on the mainland, including an independent judiciary and freedom of expression.

Those freedoms are outlined in its mini-constitution, the “Basic Law”, a document that also demands the city pass its own laws preventing treason, secession and subversion against Communist Party rulers in Beijing.

Hong Kong leaders have in the past decade put off passing Article 23, possibly their most sensitive political task, especially as tensions ran high after the months-long pro-democracy demonstrations in 2014.

But Beijing officials have not forgotten, and on Thursday Li Fei, who chairs the Basic Law Committee under the Chinese parliament’s standing committee, said it was “a duty that cannot be shirked”.

“I believe we can all see the harmful effects from this legal vacuum,” he said in a speech in Hong Kong. “I’d like to emphasize, (Hong Kong should) safeguard national sovereignty and security through legislation and strict implementation of the law.”

An earlier planned national security law for Hong Kong was shelved in 2003 after an estimated 500,000 people marched against it.

“THEIR BEHAVIOR IS ABSURD”

In his hour-long speech, live-streamed in some schools and at times directed at students, Li also lashed out at a nascent independence movement, which has gone largely underground after most of its figureheads were charged for what the government called a “riot” in 2016.

“Their behavior is absurd, the nature of it is illegal, and emotionally speaking it’s absolutely impermissible,” he said. “We must resist and oppose them without any hesitation.”

Li’s remarks came after Chinese President Xi Jinping took what some saw as a harder line on Hong Kong’s future during his visit in July to mark the 20th anniversary of the 1997 handover.

Xi warned then that any attempt to endanger Chinese sovereignty and security, challenge China’s power, or use Hong Kong to carry out infiltration or sabotage would be acts that cross “the red line” and were “absolutely impermissible”.

The city’s new leader, Carrie Lam, bent on mending the damaged trust between Beijing and the Hong Kong public, has repeatedly said the timing is not right to introduce security laws, just three years after the youth-led demonstrations directly challenged Beijing’s authority.

Even without any new local laws, some Hong Kong lawyers, diplomats and activists believe Beijing may make its own attempt to outlaw independence debates through a formal interpretation of the Basic Law, or extending national laws to cover Hong Kong.

Such moves would have to be followed by Hong Kong’s courts, deepening fears over the strength of Hong Kong’s vaunted rule of law and freedom of speech.

Some experts note that Beijing has lowered the threshold for such action after its preemptive interpretation of the Basic Law last year, which effectively disqualified lawmakers who did not take their oaths properly.

It also ruled last month to outlaw mockery of the national anthem and decided the law would be extended to Hong Kong, which will take effect after it’s been put to the city’s legislature.