Hong Kong police on Wednesday arrested four University of Hong Kong students on suspicion of promoting terrorism over a meeting held to mourn a man who killed himself after stabbing a police officer on a street.
Charles Kwok, president of a student union, and the three others could face up to 10 years in prison under the national security law if convicted, according to the South China Morning Post.
The four, aged 18 to 20, attended a meeting last month at which union council members passed a controversial motion "appreciating the sacrifice" of the assailant, according to a police statement.
The attacker seriously wounded the police officer on July 1, the anniversary of the former British colony's handover to China in 1997.
Senior superintendent Steve Li from the police's National Security Department said at a news conference on Wednesday that the meeting had involved elements of terrorism as it sought to "rationalize and glorify" the attack, adding that all four students had spoken during the meeting.
The July 7 meeting, which was livestreamed online, provoked a severe backlash from the government as well as the university, prompting the student union to retract the motion.
Members of the union's executive committee have since apologized and stepped down from their roles.
Last month, police raided the union's on-campus offices as part of an investigation into whether the group had advocated or incited terrorism in violation of the national security law.
Over several days after the attack, mourners gathered at the crime scene in the Causeway Bay shopping district to lay down white flowers in the assailant's memory.
Li warned Wednesday that acts of mourning over the incident could be prosecuted under the national security law.