The head of Hong Kong's journalist union was arrested on Wednesday, just weeks before he was set to leave the city and begin an overseas fellowship.
Ronson Chan, chairman of the Hong Kong Journalists Association (HKJA), was arrested for allegedly obstructing a police officer and disorderly conduct in a public place.
Channel C, the online news outlet Chan works for, said the veteran reporter was taken away by police officers who asked to check his identity while he was reporting on a meeting of public housing flat owners.
Police said a 41-year-old man surnamed Chan was arrested after he refused to show officers his ID card and behaved in an "uncooperative" way despite multiple warnings.
Chan was set to leave Hong Kong at the end of September for the six-month Reuters Institute fellowship programme at Oxford University.
Authorities have used a national security law and colonial-era sedition charges to crack down on dissent in Hong Kong after democracy protests three years ago.
Local media deemed critical of the government have faced a surge of police investigations and the city has plummeted down global press freedom rankings.
Like many now-shuttered civil society groups and pro-democracy unions, both Chan and the HKJA have faced repeated criticism from media outlets that answer to Beijing's Liaison Office in the city.
Police action has often followed such media coverage.
Local tabloid Apple Daily and online news platform StandNews -- which Chan used to work for -- were forced to close last year after executives were charged with national security violations, leaving hundreds of journalists out of work.
When Reporters Without Borders (RSF) released its annual press freedom ranking in May, Hong Kong had plunged 68 places to 148th in the world.
In RSF's first report in 2002, Hong Kong had some of the freest media in Asia and ranked 18th worldwide.
The Foreign Correspondents' Club of Hong Kong gave up Asia's largest annual human right press awards earlier this year, citing risks posed by the security law -- a decision that caused controversy among many journalist members.
The club recently published a watered-down statement on press freedom on its website.
One of the removed sentences from the statement read: "Facing unprecedented attacks on the media, never has our club’s role been more vital -– nor our commitment been stronger."