Hong Kong police arrested at least 40 people between Saturday night and the early hours of Sunday for a number of offences, including participating in unlawful assemblies, criminal damage and obstructing police officers.

Violent protesters threw petrol bombs at the Central Government Complex during Saturday's illegal assembly in Hong Kong. (Photo: CGTN)

"We will by no means allow the escalation of reckless violence," Yu Hoi-kwan, senior superintendent of Police Public Relations Branch said at a press conference.

"The police have the capability and determination and will try every effort to bring those outlaws to justice and let society return to normal," she added.