This article is more than 11 months old

This article is more than 11 months old

Hong Kong’s leader plans to use harsh colonial-era emergency powers for the first time, banning face masks in a bid to curb the city’s protests.

Opposition politicians warned it represented a slide towards authoritarianism and risked further inflaming tensions.

Adding to concerns about a hardline government approach, a leaked memo showed police had relaxed their guidelines on using lethal force the day before a teenage student was shot in the chest, the first live-ammunition injury since protests began in June.

Police have insisted the officer acted lawfully, and the 18-year-old student, who is still being treated in hospital, was charged with rioting and assaulting a police officer.

Hong Kong’s chief executive, Carrie Lam, was expected to announce details of the face mask ban on Friday, local media reported, in response to chaotic violence across the city on China’s national day, 1 October.

Hong Kong protests: journalist blinded in one eye as attacks on media escalate Read more

Lam was at a gala in Beijing celebrating 70 years of communist rule while pitched battles were fought in the streets of her city between police and protesters, but since her return she has been under heavy pressure from pro-China groups to use the sweeping powers bequeathed by the British.

Facebook Twitter Pinterest Carrie Lam on Tuesday arriving before the military parade marking the 70th founding anniversary of the People’s Republic of China in Beijing. Photograph: China Stringer Network/Reuters

The emergency regulations ordinance was introduced in 1922 so colonial authorities could break up strikes paralysing the ports. It allows the government to make any regulations it considers in the public interest, if it decides the city faces “an occasion of emergency or public danger”.

Measures imposed could include censorship, control or suppression of the media, arrests, detentions, deportations, and seizure of property. The legislature can only amend or repeal any law passed under the emergency regulations once it has already been implemented.

The regulations are considered so extreme that they have not been used for over half a century, and never deployed since the 1997 handover to Chinese sovereignty.

“The emergency regulations are the start of a slip towards an authoritarian state,” a lawmaker, Dennis Kwok, said at a news conference, adding that he did not expect any form of government crackdown to end the protest movement.

“The yearning for freedom, democracy and liberty are not going to go away just because you bring in more draconian regulations,” he said.

A ban on masks would appear to be a limited use of emergency powers, but government critics say they believe it could serve as a way to test public and legal reaction, and pave the way for more extensive controls.

“It will be tempting [for the government] to expand its use to other areas, such as cancelling the district council elections scheduled for November and declaring a curfew,” said Kenneth Chan, a professor at Hong Kong Baptist University and former lawmaker.

The government’s legal position has changed enormously, however, since the powers were last used in 1967, to quell riots linked to the Cultural Revolution.

Hong Kong today has its own mini-constitution, the Basic Law, which protects human rights and which some experts believe trumps even the emergency regulations.

“In my view it is incorrect to view the ordinance as a blanket power for the government,” said Stuart Hargreaves, an associate professor in the law faculty at the Chinese University of Hong Kong. “There is nothing in it that overrides the requirement that all other laws comply with the Basic Law.”

Because an anti-mask law would affect freedom of assembly guaranteed under the Basic Law, if someone challenged it a court could ask the government for a legal defence of its position, he said.

“This does not mean the government cannot introduce an anti-mask law; it means that the emergency regulations ordinance is not a trump card over constitutional rights.” Hong Kong courts had been receptive to limits on freedom of expression in the past but any ban would need to be tested, he added.

The ban aims to strike at morale and protester numbers by persuading people to stay away from gatherings for fear they will be identified. Face coverings have become a common uniform for those scared of arrest now or longer-term retaliation from Hong Kong or Chinese authorities.

But it is unclear how it would work in practice. Crowds have turned out in their thousands for demonstrations denied police permits – even though they are technically illegal.

It is also unclear whether the ban would only apply at protests or be applied more widely. Wearing face masks for health reasons is common in Hong Kong.

Activists said they expected mass displays of civil disobedience, and if large numbers still marched with face masks police would not have the capacity to arrest them all or space to hold them. However, officers might try to make an example of some individuals as a deterrent.

The fact that most police are masked – and would likely be exempt from any ban – is likely to add to frustrations.