Hong Kong’s democracy supporters were dealt a huge blow Friday as authorities postponed local elections because of the coronavirus, capping a devastating month of political disqualifications, arrests for social media posts and activists fleeing overseas.

The city’s democracy camp has come under sustained attack since Beijing imposed a sweeping national security law on the city last month — a move China’s leaders described as a “sword” hanging over the head of its critics. The ensuing weeks have radically transformed a city used to speaking its mind and supposedly guaranteed certain freedoms and autonomy in a “One Country, Two Systems” deal agreed ahead of its 1997 handover from Britain.

On Friday evening chief executive Carrie Lam, a pro-Beijing appointee, announced that September elections for the city’s legislature would need to be delayed. She described the announcement as the “most difficult decision” she has made since the pandemic began and that Beijing supported the move.

The decision will infuriate democracy supporters who had warned against any moves to delay the polls, accusing authorities of using the pandemic to avoid a drubbing at the ballot box. It also came a day after a dozen prominent democracy activists were barred from standing for election because their political views were deemed to be unacceptable.

“Our resistance will continue on and we hope the world can stand with us in the upcoming uphill battle,” Joshua Wong, one of the city’s most recognisable democracy figures, told reporters Friday before the elections were postponed. Wong was one of those disqualified, along with other young firebrand activists and some older, more moderate democracy campaigners.

“Beyond any doubt (this) is the most scandalous election fraud era in Hong Kong history,” said the 23-year-old, dressed in a T-shirt that read “They can’t kill us all”.

Hong Kong is not a democracy — its leader is chosen by pro-Beijing committees. But half of its legislature’s 70 seats are directly elected, offering the city’s 7.5 million residents a rare chance to have their voices heard at the ballot box. Planning to capitalise on last year’s huge and often violent anti-Beijing protests, democracy activists had been hoping to win their first-ever majority in September.

But officials have begun scrubbing ballot lists of candidates. Examples given by authorities of unacceptable political views have included criticising a new security law imposed by Beijing, campaigning to win a legislation-blocking majority and refusing to recognise China’s sovereignty. Earlier in the day a coalition of democracy parties warned any bid to delay the elections would be herald “the complete collapse of our constitutional system.

Around half of Hong Kong’s 3,100 COVID-19 cases have been detected in the past month and authorities fear hospitals are on the verge of being overwhelmed. According to the International Institute for Democracy and Electoral Assistance, at least 68 elections worldwide have been postponed because of the virus, while 49 went ahead.

Hong Kong is going through its most politically turbulent period since its return to Chinese rule, and last year seven straight months of pro-democracy protests swept the city. The pandemic and mass arrests have helped throttle the movement, but anger towards Beijing still seethes. In response, China imposed its security law on June 30, bypassing the legislature and keeping the contents of the law secret until it was enacted.

Beijing said the law would restore stability and not impact political freedoms. It targets four types of crime — subversion, secession, terrorism and colluding with foreign forces — with up to life in prison.

But the broadly worded law instantly outlawed certain political views such as promoting independence or greater autonomy for Hong Kong. One provision bans “inciting hatred” towards the government. Critics, including many Western nations, say it has demolished the “One Country, Two Systems” model. Since it came into force, some political parties have disbanded while at least three prominent Beijing critics have fled overseas. Libraries and schools have pulled books deemed to be in breach of the new law.

At least 15 arrests have been made so far. On Wednesday four students were arrested under the new law for “inciting secession” through posts on social media. Others have been arrested for shouting pro-independence and other protest slogans or possessing objects emblazoned with them. All were bailed on Friday.

A man who allegedly drove his motorbike into a group of police officers while flying an independence flag was the first to be charged under the law, with terrorism and secession offences.