HK police make first arrest under new law

Hong Kong police display a banner warning protesters not to breach the law

Hong Kong police have detained a man holding a flag that appeared to urge independence, the first arrest under a sweeping national security law introduced overnight, but the fine print on the man's banner raised questions about his call.

Pictures posted by police on Twitter showed the black flag with "Hong Kong independence" written in large English letters and Chinese characters.

"This is the first arrest made since the law has come into force," police said of the man, seen in one picture wearing a black T-shirt with "Free Hong Kong" on it.

But a closer look at the picture showed a minuscule "no to" written in front of the call for independence.

Police did not immediately respond to a request for comment and it was not clear if the small letters would save the man from prosecution. There was no other detail about the man.

Twitter users were left scratching their heads.

"The flag says 'No to Hong Kong Independence'. Is that subversive, too?" one user asked.

"No one read the fine print," said another.

The security law, introduced by Beijing, punishes crimes of secession, subversion, terrorism and collusion with foreign forces with up to life in prison.

Waving an independence flag could be considered a crime of secession.

China says Hong Kong is an inalienable part of the country and calls for independence are anathema to the ruling Communist Party.