New Delhi, May 30 -- A prominent Hong Kong journalist began serving a five-day prison sentence Friday after losing an appeal against his conviction for obstructing a police officer in a case that sparked concerns about the city's declining press freedom.

Hong Kong was once a bastion of media freedom in Asia, but news outlets have been forced to close, some journalists have been arrested and those still working are operating in a narrower space since authorities began cracking down on activist voices following the mass pro-democracy protests in 2019.

Ronson Chan, a former chair of the Hong Kong Journalists Association, was arrested in September 2022 on his way to a reporting assignment. He was accused of refusing to show the plainclothes...