It comes a day after three prominent young democracy campaigners - including Joshua Wong - were jailed for taking part in last year's democracy protests.
Hong Kong media tycoon Jimmy Lai was remanded into custody on Thursday after being charged with fraud, the latest in a string of prosecutions brought against high-profile Beijing critics and democracy campaigners.
Mr Lai, 73, is the owner of Hong Kong's best-selling Apple Daily, a popular tabloid that is unashamedly pro-democracy and fiercely critical of authorities.
He and two of the firm's executives - Royston Chow and Wong Wai-keung - face fraud charges that court documents say are related to the paper's offices allegedly being used for purposes not permitted by the building's lease.
Police raided Apple Daily's headquarters in August and arrested a string of senior company figures, including Mr Lai, on suspicion of "collusion with foreign forces" under a vaguely worded new national security law that Beijing imposed on the city.
None has so far been charged with any national security breaches.
But Victor So, the magistrate overseeing Thursday's hearing, is from a group of judges selected by Hong Kong's chief executive to try such cases.
Mr So denied Mr Lai bail but granted it to Mr Wong and Mr Chow, setting the next court date for April.
The decision means Mr Lai, who was later photographed arriving at prison with his hands cuffed, faces months behind bars as police continue their investigation.
China's clampdown on Hong Kong has dramatically accelerated since it imposed its sweeping security law in June, with opposition politicians disqualified and dozens of activists charged or investigated.
On Wednesday, three prominent young democracy campaigners - including Joshua Wong - were jailed for taking part in last year's democracy protests.
Mr Lai is also being prosecuted for his alleged part in those rallies in a separate prosecution.