Police said on Thursday evening that their national security department had launched an investigation into a protest at Chinese University earlier in the day.

The force said protesters had displayed Hong Kong independence banners and chanted slogans calling for independence, and they were suspected of breaching the national security law.

Police said there were also alleged incidents of criminal damage, noting that it was the university itself that reported the matter to the force.

Meanwhile, the Education Bureau condemned the organisers of a march at the university.

It said a university campus is not a lawless place, and no student or staff can commit acts that "threaten national security".

The bureau also said it supports the decision by university management to call in the police.

Dozens of people wearing black graduation gowns and face masks took part in the protest action, which came a little over a year since the fierce clashes between police and protesters at the campus in Sha Tin.