HONG KONG (Reuters) - A Hong Kong judge kept 47 pro-democracy activists in custody on Thursday after four days of bail hearings in a case that has drawn global concern that Beijing is using a national security law to crush dissent. Thirty-two defendants were denied bail by chief magistrate Victor So, while 15 were granted bail but still kept in custody after government prosecutors said they would appeal against that decision. The case is the most sweeping use yet of the city’s new national security law, which imposes punishments of up to life in prison for serious charges including subversion. There were emotional scenes at the West Kowloon court, as some sobbed inside the chambers and others hugged outside. One person stood outside the court with a yellow umbrella, a symbol of the democracy movement, and a banner that said “Free all political prisoners”. “We’re not surprised at all that today’s bail application failed,” said Po-ying Chan, wife of one of the prominent defendants who was denied bail, “Long Hair” Leung Kwok-hung. “This proved that under the NSL (national security law), the legal system has been twisted and turned upside down.” Foreign diplomats and rights groups are closely monitoring the case as concerns mount over the vanishing space for dissent in the former British colony, which has taken a swift authoritarian turn since the imposition of the law in June 2020. The hearings have gone on late into the night for three consecutive days, causing several defendants to fall ill and be taken to the hospital. This has raised concerns among rights groups and some foreign diplomats over their treatment. The 15 defendants granted bail are now expected to appear for another hearing within 48 hours at the High Court. For the others -- including Leung and prominent activists Owen Chow, Lester Shum, Wu Chi-wai, Eddie Chu, Alvin Yeung, Claudia Mo, Gwyneth Ho and Prince Wong -- the case was adjourned until May 31. Some defendants had pledged to leave the political scene for good and to quit their parties. “VICIOUS PLOT” Slideshow ( 4 images ) Hong Kong laws restrict media coverage of the content of bail hearings. An appeal to lift those restrictions in the interests of transparency was rejected by the court on Thursday. In contrast with the global financial hub’s common law traditions, the new security law puts the onus on defendants to prove they will not pose a security threat if released on bail. The activists, aged 23-64, are accused of organising and participating in an unofficial, non-binding primary poll last July that authorities said was part of a “vicious plot” to “overthrow” the government. The vote was aimed at selecting the strongest opposition candidates for a legislative council election that the government later postponed, citing the coronavirus. The detentions have been fiercely criticised by governments in the West, including in Britain and the United States. Hong Kong’s Department of Justice has said no one should interfere with independent prosecutorial decisions, which would undermine the rule of law. Supporters of the security law, which punishes what it broadly defines as secession, subversion, terrorism and collusion with foreign forces with up to life in prison, say it is necessary to restore stability in Hong Kong after months of pro-democracy protests in 2019. As China’s rubber-stamp parliament opens this week, Beijing is expected to further curb the influence of any remaining opposition in Hong Kong by changing the way legislators and the chief executive are elected. Beijing has also flagged “reforms” for Hong Kong’s judiciary. Critics say that could hurt the independence of the legal system, a foundation of the city’s prosperity. Hundreds of people gathered at the court to show their support for the defendants, though the numbers were much lower than on Monday, when about 1,000 supporters chanted democracy slogans in scenes reminiscent of 2019.