Several Hong Kong activists arrested under security law

Hong Kong police has arrested 53 people in a swoop on anti-Beijing activists in an operation that involved about 1,000 national security officers, the biggest crackdown yet on the Chinese-ruled city's opposition camp.

Li Kwai-wah, senior superintendent of police under the national security department, was speaking at a press briefing shortly after Secretary for Security John Lee said the government will not tolerate "subversive" acts.

The latest police operation comes as China stamps out opposition to its rule in the semi-autonomous business hub after millions hit the streets in 2019 with huge and sometimes violent anti-Beijing protests.

Opposition figures and parties took to their Facebook and Twitter accounts to confirm at least 21 arrests, most on a charge of "subversion".

The police sweep netted a swathe of opposition figures, from veteran former lawmakers such as James To, Andrew Wan and Lam Cheuk Ting to a host of younger activists.

Among the youth campaigners who confirmed their arrests via Facebook were Gwyneth Ho, a 30-year-old former journalist turned social activist, and Tiffany Yuen, a 27-year-old district councillor.

Colleagues of Joshua Wong, one of the city's most famous activists who is currently in jail, said via his official Facebook account that his home was searched by police in the same operation.

In addition to that, police entered the law firm of former Hong Kong Democratic Party lawmaker Albert Ho, a security guard told Reuters.

READ MORE: Chinese court sentences 10 Hong Kong activists for border crossing

China backs implementation of 'duties'

China said it supports Hong Kong authorities in the fulfillment of their duties after the mass arrest.

Hong Kong people's rights and freedoms according to the law are not affected, foreign ministry spokeswoman Hua Chunying told a regular news briefing.

Campaigning for win a crime

Opposition figures said the arrests were linked to a primary organised by anti-Beijing parties last year ahead of local legislative elections which were ultimately scrapped altogether.

More than 600,000 Hong Kongers turned out to vote in the unofficial primary, which was aimed at picking who would stand for election in Hong Kong's legislature – a body where only half the 70 seats are popularly elected.

The aim of the campaign was to win all 35 elected seats and take a majority in the legislature for the first time.

At the time, Beijing officials had warned that campaigning to win a majority constituted "subversion" under the new security law.

Arrested live on Facebook 

Ng Kin-wai, a district councillor, broadcast the moment police came to his home live on Facebook.

"I am now arresting you for the offence of subversion," the arresting officer said.

"You participated in a primary election named '35+ citizens vote' in the year 2020 in order to elect 35 or more winners to join the Legislative Council."

The officer said the campaign was "aimed at seriously interfering in, disrupting, or undermining" the government and was a justification for the subversion charge.

Robert Chung, a political pollster who helped organised the primary, was also among those arrested on Wednesday according to his colleague Chung Kim-wah.

The national security law was imposed on Hong Kong in late June in response to the 2019 protests.

The broadly worded law targets acts Beijing deems to be secession, subversion, terrorism and collusion with foreign forces.

The legislation bypassed the city's legislature and was kept secret until the moment it was enacted.

READ MORE: More arrests in Hong Kong as crackdown on dissent continues

"One Country, Two Systems"?

Officials said the security law would only target an "extreme minority".

But it swiftly silenced dissent and outlawed a host of peaceful political views with dozens of prominent figures arrested even before Wednesday's operation.

Over the course of the last year, prominent anti-Beijing figures have been arrested, jailed, barred from politics or have fled overseas.

Some have had their assets frozen, or families locked out of bank accounts.

National security crimes carry a maximum of life in prison and bail is not usually granted for those who are charged.

Others have been jailed for organising or taking part in protests.

The law also toppled the legal firewall between Hong Kong's independent judiciary and the mainland's Communist Party-controlled courts.

China has claimed jurisdiction over especially serious security crimes and has allowed its security agents to operate openly in the city for the first time.

Multiple Western nations have accused Beijing of shredding the "One Country, Two Systems" agreement where it promised Hong Kong could keep certain liberties and autonomy ahead of its 1997 handover by Britain.

Washington has sanctioned key official because of the security law, including Hong Kong's leader Carrie Lam.

Beijing has defended the law as a necessary measure to restore stability.

READ MORE: Hong Kong activist and media mogul Jimmy Lai charged under security law