The court is weighing whether to grant bail to the activists, who were detained and charged Sunday over their involvement in an unofficial primary election last year that authorities say was part of a plot to paralyse Hong Kong''s government.

Less than half of the bail proceedings were heard on Monday when the court adjourned the session at about 2 a.m. The hearing resumed later Tuesday morning, although at least four defendants who were taken to the hospital in the early hours of Tuesday were not present in the morning session.

The national security law, which China imposed on Hong Kong last June in response to months of anti-government protests, makes it a crime to overthrow, seriously interfere in, disrupt or undermine Hong Kong''s government.

The law, which also criminalises acts that incite Hong Kong''s secession from China, collusion with foreign powers and terrorism, has largely silenced protest in the semi-autonomous Chinese territory.

The 47 activists, who include prominent leaders such as Joshua Wong and Benny Tai, were among 55 arrested in January on suspicion of subversion in what was by far the biggest sweep by police since the security law''s enactment. The 47 were formally charged Sunday. Authorities have not said whether the other eight will be charged.

Defense lawyers are fighting against a bid by the prosecution to remand the activists in custody for three months while police conduct investigations, arguing that the activists should not have been charged if the case against them was not ready.

A clause under the national security law specifies that bail will not be granted to suspects unless the judge has sufficient grounds to believe that defendants “will not continue to commit acts endangering national security."

Hundreds of supporters gathered outside the courthouse Monday, displaying slogans in favour of the 2019 pro-democracy protests advocating greater local autonomy. Some chanted protest slogans such as “Liberate Hong Kong, revolution of our times" — which the Hong Kong government has said has secessionist connotations and thus could contravene the national security law.

China has cracked down hard on such calls, demanding changes to the legal and educational systems to inculcate loyalty to the ruling Communist Party.

Hong Kong''s security secretary, John Lee, defended the national security law at a webinar Monday during a UN Human Rights Council meeting.

“The effect of the law is obvious and direct,” he said, according to a transcript. “Violence has dropped significantly. Advocacy of Hong Kong independence'' subsided."

The 47 charged this week were involved in primaries held by the pro-democracy camp last year to determine the best candidates to field to try to win a majority in the legislature.

If the pro-democracy camp had won a majority, at least some members of the camp had plans to vote down major bills that would eventually force Hong Kong leader Carrie Lam to resign. Authorities said the activists'' participation in the primary was part of a plan to paralyse the city''s legislature and subvert state power.

Human Rights Watch said Hong Kong should drop the charges against the activists. “The Hong Kong authorities are using the Beijing-imposed National Security Law to wrongfully charge 47 people who sought peaceful change through the democratic process,” Maya Wang, senior China researcher at the New York-based organization, said in a statement.

Nearly 100 people have been arrested under the national security law. Serious offenders could face life imprisonment.