The government of China's Hong Kong Special Administrative Region (HKSAR) and the Hong Kong police condemned the continued violent acts of radicals, which put public safety in jeopardy.

An unlawful assembly in Hong Kong turned violent again on Sunday as radical protesters vandalized subway stations, set fires and hurled petrol bombs.

"Multiple protesters assembled and blocked the roads in Causeway Bay, Wan Chai and Admiralty today (Sunday), paralyzing traffic in various districts and seriously affecting people's lives," said a spokesman of the HKSAR government late on Sunday.

"They set fires at various places, which were fierce at one point, and hurled petrol bombs on the streets as well as into a MTR (Mass Transit Railway) station and at the Mong Kok police station, posing a grave threat to police officers, MTR staff and members of the public at the scene," he said.

The HKSAR government "severely condemns the radical protesters who completely disregard law and order and whose acts seriously undermine social order," he said. "The police will continue to take law enforcement actions resolutely to protect the safety of members of the public and restore public order."

The police later issued a statement, saying that the demonstration on Sunday was unauthorized, which soon turned violent and destructive as protesters charged police cordon lines, set fires at the entrances and exits of MTR stations, torched banners, threw hard objects at police vehicles and government buildings, hurled numerous petrol bombs at police officers and a police station, and assaulted people who hold different views, causing serious injuries.

"Having given repeated warnings but in vain, officers conducted dispersal operations with appropriate force, including tear gases, rubber bullets, bean bag rounds and 40mm react rounds," said the statement.

One police officer was forced to fire a warning shot into the sky as some police officers were surrounded and attacked by a large group of violent protesters, and their lives were under serious threat.

"Police reiterate that no violent acts will be tolerated," said the statement. The police will continue to take resolute enforcement action so as to safeguard public safety and bring all lawbreakers to justice, it said.