China's central government on Tuesday condemned the ransacking of Hong Kong's legislature and said it backed the city authorities to investigate the "criminal responsibility of violent offenders".
Hong Kong is in crisis after weeks of massive demonstrations over a bill that would allow extraditions to the Chinese mainland.
On Monday, the 22nd anniversary of the city's handover to China, groups of mostly young, hardline protesters, broke into the legislative council where they hung Hong Kong's colonial-era flag and left anti-Beijing graffiti.
"These serious illegal actions trample on the rule of law in Hong Kong, undermine Hong Kong's social order and harm the fundamental interests of Hong Kong," the Hong Kong and Macao Affairs Office of the State Council, China's cabinet, said in a statement by an unnamed spokesperson.
"It is a blatant challenge to the 'one country, two systems' bottom line. We express our vehement condemnation against this," the spokesperson said.
Under the terms of the 1997 handover between colonial power Britain to China, Hong Kong is to be governed under its own laws with special rights including freedom of speech and an independent judiciary until 2047.
Meanwhile Hong Kong's leader Carrie Lam held a pre-dawn press conference on Tuesday morning in which she condemned what she called the “extreme use of violence” by the protestors who stormed and vandalized the territory's parliament.
She said “nothing is more important than the rule of law in Hong Kong”.