Police said three men and one woman, aged 16 to 21, were arrested.
Although police declined to name the group or the detainees, the political group Studentlocalism said on Facebook that its members were among the detainees, naming one as former leader Tony Chung.
At a news conference late Wednesday, police spokesman Li Kwai-wa said the organization had “posted information about the creation of a new party advocating for Hong Kong independence on social media.”;
“We have to obey the law, even if the crimes are committed online. Don’t think you can escape responsibility in cyberspace and commit crimes,” Lee added.
Police said four were being investigated under sections 20 and 21 of the Security Act, which deal with secession. According to the law, secessionist crimes of a “serious nature” can result in a sentence of at least 10 years and life imprisonment, while minor crimes are punishable by three to 10 years.
On Sunday, the group published a post entitled “Fighting Chinese Nationalism, Build Hong Kong Nationalism,” which links to a Facebook page and a recruitment form for the “American Student Division of Hong Kong.” The page of the US group states that “it is obliged to advance the path of the citizens of Hong Kong to the return of our right to self-determination and to advance the path of Hong Kong to independence.”
Shortly after the arrests, a CNN reporter had a source to cancel an interview not related to the security law, “given the latest development in Hong Kong.”
In a statement, Sophie Richardson, China’s director of Human Rights Watch, said the arrests were “a gross abuse of this draconian law (which makes it clear) that the purpose is to silence dissent, not to protect national security.”
She added that they were “concerned about the wider struggle against political parties” over the approach to the September legislative elections.
However, the chance of holding this election this week has been questioned, with reports that the government may use emergency powers to hold them until 2021, due to the recent rise in coronavirus cases in Hong Kong.
The election period ends on Friday, and the polls are scheduled to open on September 6.
More than 100 new coronavirus infections have been reported in the city each week in the last week, exceeding zero in late June. Wednesday marked the first day of the harshest social exclusion measures Hong Kong has seen so far: masks designed indoors and outdoors, no more than two people per group when gathering in public, and no canteen in a restaurant.
Ronnie Tong, a member of Hong Kong’s executive council or de facto cabinet, told CNN that he did not know how long the delays could be, but that any decision to postpone the election would be due to public safety concerns.
“I hope people understand that any delay is about community safety, not political considerations. The people of Hong Kong still have the right to vote freely,” Tong said.
City registries and ballots said they were “closely monitoring” the coronavirus outbreak in the city and its potential impact on the election, and “will listen to the advice of the government and health experts.”
Pro-democracy activists rejected any proposal to postpone the election. Activist Joshua Wong said the pandemic was a pretext, adding that the government was “afraid they would suffer landslides in the upcoming elections.”
Opposition parties aimed to shift the government’s wave of discontent to a historic victory in a semi-democratic legislature, where just under half of the seats are controlled by so-called functional constituencies, which represent business and society and are generally pro-government.
Last year, candidates for democracy won local elections. Such a result in the legislature could allow them to force a constitutional crisis by blocking the budget and pushing the Lama to resign. Both the Chinese government and Hong Kong have suggested that such a plan could be illegal under the new national security law.
CNN’s Isaac Ye, Vaness Chan, Philip Van, Jadin Sham and Sarah Fidel submitted reports.