China had already lodged "stern representations" with the United States about the Hong Kong-related bill and urged that it not be passed into law, Chinese Foreign Ministry spokesperson Geng Shuang said at a press briefing on Wednesday.

His comments came after the chairman of the U.S. Senate Foreign Relations Committee said on Tuesday he wanted the Senate to pass legislation to support protesters in Hong Kong.

Read more: How Hong Kong act is a backdoor for U.S. goals

Geng accused the U.S. senator of turning a blind eye to the protesters' rampage and instead trumpets their radical and violent acts, with the ultimate aim to undermine Hong Kong's stability and prosperity and contain China's development.

Warning the passing of the bill would harm China-U.S. relations and also America's own interests in the region, Geng said "China will take vigorous, reciprocal actions, to staunchly safeguard our sovereignty, security and interests, in response to the wrong actions of the U.S. side".

"Hong Kong is not having problems with the so-called issues of human rights and democracy," he added, stressing that the pressing issue facing Hong Kong is to stop violence, restore order, as well as maintain the rule of law.  

Tensions in Hong Kong have escalated this week as rioters called for a general strike and attempted to paralyze traffic by trashing transport facilities and obstructing roads, causing all schools in the city to suspend classes on Thursday for safety reasons. 

Rioters have already turned major university campuses across the city into battlefields, where their violent acts posed deadly threats to police officers and everyone at the scene.

Video footage showed hundreds of student protesters throwing petrol bombs, bricks, launching arrows and even firing a signal flare at police officers during the standoff. 

HKSAR Chief Executive Carrie Lam said earlier on Tuesday that protesters were being "extremely selfish" and urged teachers and students not to engage in political activities at schools.

"I want to reaffirm that Hong Kong is China's Hong Kong and Hong Kong affairs are China's internal affairs. It cannot be interfered with by outside powers," Geng said.

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HK police: it is impossible to gain solution through violence

China strongly condemns the escalation in violence in Hong Kong