HONG KONG — The Hong Kong police arrested dozens of elected pro-democracy officials and activists early Wednesday for their involvement in an informal primary, the largest roundup yet under the new national security law imposed by Beijing to quash dissent.
The wide-ranging arrests — which included figures who had called for aggressive confrontation with the authorities and those who had supported more moderate tactics — underscored Hong Kong officials’ efforts to weaken any meaningful opposition in the city’s political institutions. The move on Wednesday suggested that the authorities were casting a wide net for anyone who had played a prominent role in opposing the government.
The national security law, which was passed by the Chinese Communist Party in June, has been wielded as a powerful tool to crack down on the fierce anti-Beijing protests that upended the city for months. Since then, the Hong Kong authorities have detained pro-democracy leaders, raided news media offices and ousted opposition lawmakers.
The Hong Kong police did not immediately identify those arrested, but said 53 people had been detained. Li Kwai-wah, a senior police superintendent, said at a news conference on Wednesday that about 1,000 police officers had arrested them under the national security law in relation to the primary, including six organizers and 47 participants. They also searched 72 places and froze more than $200,000 in funds related to the effort.
The police also visited the offices of at least one law firm and three news organizations to demand documents, broadening the burst of arrests that started before sunrise and sent a chill through Hong Kong’s already-demoralized opposition camp.
Along with detaining activists, the authorities arrested at least 10 former Legislative Council members, an American lawyer who has been involved in the pro-democracy movement and a number of district councilors, a hyperlocal elected position dominated by pro-democracy figures. Before the latest roundup, the police previously arrested dozens of people under the national security law, including Jimmy Lai, the media mogul and founder of Apple Daily, a pro-democracy newspaper.
“This is a total sweep of all opposition leaders,” said Victoria Hui, an associate professor of political science at the University of Notre Dame who studies Hong Kong. If running for office and trying to win election are considered subversion, she added, then the security law “is aimed at the total subjugation of Hong Kong people.”
“There should be no expectation of elections in any sense that we know it if and when elections are held in the future,” Ms. Hui said.
The unofficial primary, which was held in July, was organized by the pro-democracy camp in an effort to pare down the number of candidates in the September election for Hong Kong’s Legislative Council. Dozens of candidates had expressed interest in running despite a voting system that gives significant advantages to establishment candidates. The pro-democracy camp, which had a long shot of winning a majority, had wanted to try to ride the momentum created by the landslide defeat of establishment candidates in the 2019 district council elections.
If they had managed to win, many of the opposition candidates said they had planned to use that majority to block the government’s agenda, including vetoing the annual budget. If the budget is vetoed twice, the chief executive would be forced under Hong Kong law to step down.
Government officials had warned that such a plan could be considered subversion under the national security law. The September election never took place. The Hong Kong government postponed it in late July by one year, citing coronavirus concerns. Many democracy supporters accused officials of trying to prevent an embarrassing loss for the pro-Beijing camp.
The authorities have been steadily taking aim at pro-democracy forces. The Hong Kong government disqualified several pro-democracy candidates from running in the election for the Legislative Council. In November, the government disqualified four pro-democracy incumbents who it said had supported or had been inadequately critical of U.S. sanctions on the city. The remaining opposition members resigned in protest.
More than 600,000 Hong Kongers voted in the July primary election, largely selecting newer candidates who favored a more aggressive approach toward the government, rather than more familiar moderate faces. Some of the activists arrested on Wednesday were among the more outspoken winners. But the police also arrested candidates who had lost their primary races and were less directly involved with the mass protests.
In a Facebook Live video streamed by Ng Kin Wai, a district councilor, as the police arrived at his door on Wednesday, an officer could be heard saying that he was arresting Mr. Ng on suspicion of “subversion of state power.” The officer says he has “reason to believe” that Mr. Ng had participated in the primary in order to win office and ultimately “force Chief Executive Carrie Lam to resign.”
Au Nok-hin, a former Legislative Council member who helped organize the primary, was also arrested on Wednesday. He had stepped down from his organizing role after the government warned the effort could amount to subversion.
The Twitter account of Joshua Wong, the former student leader who is one of the most prominent faces of the Hong Kong protests, said that the police had also raided Mr. Wong’s home on Wednesday morning because he had participated in the primary.
Mr. Wong is serving more than a year in jail for his role in a 2019 protest, a charge not linked to the national security law. Convictions under the security law can lead to significantly longer sentences.
Also on Wednesday, police officers delivered a court order to Stand News, a news organization seen as supportive of the protests, requesting documents. They raided the offices of Apple Daily last year.
They also arrested John Clancey, an American lawyer, and searched the offices of the firm where he worked, according to Jonathan Man, another lawyer at the firm.
Human rights groups and government officials overseas condemned the mass arrests.
Maya Wang, senior China researcher at Human Rights Watch, said the authorities had removed “the remaining veneer of democracy in the city.”
“Repression generates resistance,” Ms. Wang said in a statement, adding that “millions of Hong Kong people will persist in their struggle for their right to vote and run for office in a democratically elected government.”
Antony Blinken, President-elect Joseph R. Biden Jr.’s nominee for secretary of state, wrote on Twitter that the arrests were “an assault on those bravely advocating for universal rights.” He said the incoming administration would stand with Hong Kong against Beijing’s crackdown.
Tiffany May contributed reporting.