New Delhi, Jan. 21 -- Two former leaders of a Hong Kong pro-democracy group that for decades organized a vigil commemorating people killed during Beijing's 1989 Tiananmen crackdown are set to stand trial in a case brought under a national security law that has all but silenced dissent in the city.

A third co-defendant is expected to plead guilty at Thursday's hearing.

Observers say the disappearance of the only large-scale public commemoration of the 1989 crackdown within China is part of a decline in Western-style civil liberties, which Beijing promised to maintain for 50 years when it took control of the former British colony in 1997.

The government said its law enforcement actions were evidence-based and strictly in accordance with ...