Yang Guang, spokesman of the Hong Kong and Macao Affairs Office of China's State Council, said he hoped people "from all walks of life in Hong Kong will clearly oppose and resist violence".

Yang said the violence, which he blamed on a "few radicals", had seriously undermined Hong Kong's prosperity and stability, and "bumped into the bottom line" of the "one country, two systems" principle that governs the financial hub.

"No civilized society or rule of law society will tolerate rampant violence," Yang said at an extraordinary press conference.

"We hope that the general public will clearly understand the seriousness of the current state of affairs and jointly denounce the bad actions and crimes committed by radicals, and prevent them from harming Hong Kong," he said.

Yang said the central government "strongly" supports Hong Kong's beleaguered chief executive Carrie Lam and the city's police force, which has been accused of using excessive force against protesters.

"We also believe that Hong Kong's top priority task right now is to punish violent and unlawful acts in accordance with the law, to restore social order as soon as possible, and to maintain a good business environment," said another Hong Kong affairs spokeswoman, Xu Luying, at the press conference.