Lawyers in Hong Kong on Tuesday hit out at a statement from China's National People's Congress (NPC) standing committee questioning a decision in the city's High Court that overturned a ban on the wearing of masks as unconstitutional.

Hong Kong's High Court on Monday found that an Oct. 4 mask ban passed by the administration of chief executive Carrie Lam under colonial-era emergency legislation was excessive and unconstitutional under the city's mini-constitution, the Basic Law.

But the NPC standing committee's legislative affairs commission said Hong Kong courts had no power to rule on constitutionality, a claim that was refuted by Hong Kong's Bar Association on Tuesday.

Beijing's Hong Kong and Macau Affairs Office also expressed concern at the ruling, as did Xie Chuntao, a deputy director of the Communist Party's Central Party School.

"Who has the right to interpret the Basic Law of Hong Kong? It is ... very clear that only the NPC Standing Committee does, and any other organisation does not," Xie said in Beijing.

And China's state news agency Xinhua quoted the principal official of the Beijing's Central Liaison Office in Hong Kong as saying that "the administrative, legislative and judicial bodies of the Hong Kong Special Administrative Region should respect relevant decisions of the NPC standing committee when performing their duties and exercising relevant powers in accordance with the law.”

The HKBA said the comments from Beijing were legally incorrect.

"The Courts in Hong Kong have previously struck down unconstitutional laws," it said in a statement on its website. "There was no suggestion previously that the Courts cannot do so."

"For a court not to decide any case which argues that a legislative provision is contrary to the Basic Law is to fail to uphold the Basic Law, which every judicial officer has sworn to do," it said.

It cited Article 160 of the Basic Law as saying that laws later found to be in contravention of the Basic Law can be amended or "cease to have force."

Rule of law undermined

And Article 19 stipulates that Hong Kong shall be "vested with independent judicial power, including that of final adjudication," it said.

It said calls for an interpretation of the Basic Law by the NPC standing committee before a judicial matter has been concluded undermine the rule of law.

NPC standing committee member Tam Yiu-chung said the decision was "inappropriate" and "in need of rectification."

Tam said either the case will go to the Court of Final Appeal, or Beijing should make an interpretation of the Basic Law, a possibility that could be discussed at the standing committee's next meeting in late December.

Pro-democracy lawmaker Dennis Kwok, who represents the legal profession in Hong Kong's Legislative Council (LegCo), said the comment from the NPC could have serious implications for the city's legal system.

"Now we have the legislative affairs committee of the NPC saying that no court has the power to rule on such things," Kwok said. "If they're not even allowed to rule on whether or not a law passed by the Hong Kong government is constitutional or not, then I would ask the legislative affairs committee to respect the separation of powers in Hong Kong and its common-law system based on the Basic Law."

"If they can't even respect that, then one country, two systems really is dead," he said, in a reference to promises by the ruling Chinese Communist Party to allow Hong Kong a "high degree of autonomy" as a separate jurisdiction from mainland China, under the terms of the 1997 handover.

Legal experts said that if the government appeals the decision, the ultimate decision could rest with the NPC standing committee as the final interpreter of the Basic Law, which could be tempted to overturn a fundamental power of Hong Kong's legal system, further undermining the city's autonomy after a string of interpretations affecting its political life in recent years.

Civic Party lawmaker Alvin Yeung said any further interpretation by the NPC at this time could "fan the flames" as the city is in the grip of pro-democracy protests sparked by widespread fears for its freedoms.

"This statement from the legislative committee will only ... fan the flames of the situation," Yeung said. "If anyone tries to deal with this ... by resorting to interpretations, it won't resolve anything: it'll only make things worse."

Detentions in China

Lam declined to comment for the time being, saying that the government has always respected court rulings in the past.

Meanwhile, authorities in China have been detaining people for commenting on the pro-democracy movement in Hong Kong, as internet users said the virtual private networks (VPNs) they rely on to see news not approved by Beijing are working only intermittently.

Authorities in the southeastern province of Fujian have detained a government official for commenting on the protest movement, a citizen journalist surnamed Wang told RFA.

"This person is from Fuzhou," Wang said. "He has just gotten home after being detained for five days."

She said police had accused him of "insulting the Communist Party" and "posting anti-social speech" online.

Chinese censors have banned internet users from posting or forwarding social media content about Hong Kong since the anti-extradition movement escalated in early June, later broadening into a movement demanding fully democratic elections and accountability for police violence.

Photos posted to the social media site WeChat are soon deleted, and the only Hong Kong-related content is from officially sanctioned state media, which characterizes the protest movement as separatist rioters.

Border guards are also checking the phones of anyone crossing the border into mainland China from Hong Kong, sources told RFA.

"Checks on mobile phones, reading materials and various other items that come in from overseas are very strict indeed," a source surnamed Huang said. "They are strictly controlled when going through border checks coming in and out of Hong Kong and enter mainland China."

He said he knows of a number of internet users in the southwestern province of Guizhou who have been called in for questioning, detained or warned not to talk about Hong Kong after they discussed the protests online.

"They are ... cracking down on them very hard," Huang said.

Reported by Qiao Long for RFA's Mandarin Service, and by Sing Man for the Cantonese Service. Translated and edited by Luisetta Mudie.