Beijing warned it would retaliate if United States President Donald Trump signed the Hong Kong Human Rights and Democracy Act into law, after the US Senate passed the act, which could pave the way for diplomatic action and economic sanctions against the city's government.
Chinese foreign ministry spokesman Geng Shuang said that any attempt by the US to interfere in China's internal affairs would be in vain, following the passage of the act through an expedited process.
"We call on the US side to take a clear look at the situation and take steps to stop the act from becoming a law, and stop meddling in the internal affairs of China and Hong Kong, to avoid setting a fire that would only burn itself," Geng said in a statement.
"If the US sticks to its course, China will surely take forceful measures to resolutely oppose it to safeguard national sovereignty, security and development interest."
Geng said the move by the US Congress' upper chamber was a serious violation of international law and international relations norms, which China "strongly condemns and opposes".
The situation facing Hong Kong, where there has been over five months of anti-government protests, was not about human rights and democracy, but about stopping violence and restoring order, Geng said.
He said violent acts had jeopardised social order and challenged the "one country, two systems" principle under which Hong Kong retained certain freedoms and a degree of autonomy after its 1997 handover from Britain to China.
The bill's passage in the Senate came after the House of Representatives passed its version last month. The Senate also passed the Protect Hong Kong Act, which would prohibit the export of non-lethal crowd control and defence items to Hong Kong.
The House and Senate versions of the Hong Kong Human Rights and Democracy Act will need to go to a committee of House and Senate members to be reconciled into one unified bill that will go back to each chamber for final approvals. Trump will then have 10 days to sign the bill into law or veto it.
Both versions of the bill would require the US government to produce an annual report, certified by the secretary of state, on whether Hong Kong had retained enough autonomy from Beijing to retain the distinct trading status that protects the city from the tariffs the US imposed on Chinese imports last year.
The bill also calls for sanctions against any individuals or entities deemed to have violated freedoms guaranteed under Hong Kong's Basic Law, its mini-constitution.
The number of senators co-sponsoring the Hong Kong Human Rights and Democracy Act surged on Monday, bringing in Senate Republican leader Mitch McConnell and showing the biggest jump since the bill was introduced in June. The surge followed a stream of reports about a violent stand-off since Sunday between Hong Kong's police and radical protesters at the Hong Kong Polytechnic University.
Many US lawmakers have blamed Beijing and the Hong Kong government for the cycle of violence in recent months that has culminated in the university melee.
The Hong Kong government expressed regret about the passage of the two US acts, saying they were unnecessary and groundless. It said in a statement that the acts would hurt both Hong Kong and US interests.
The Secretary for Commerce and Economic Development of Hong Kong, Edward Yau Tang-wah, criticised what he called an "unwarranted and unnecessary" act for "adding fuel to the fire".
"I don't want people to be mistaken: the unwarranted foreign intervention is adding fuel to the fire in Hong Kong," he said. "I don't see any possible ways to de-escalate the situation we are having. So I would urge people to refrain from meddling into the already delicate situation."
Several other Beijing bodies denounced the passage of the bill. Yang Guang, spokesman for the State Council's Hong Kong and Macau Affairs Office, Beijing's highest policy office on Hong Kong matters, expressed "strong protest and condemnation".
"Some extreme acts of violence are devastating and horrifying," Yang said. "These facts clearly prove that the biggest risk facing Hong Kong now is violence, not the issue of 'human rights' and 'democracy'.
"The act by some American politicians has completely mixed up right and wrong, and is a double standard without any principle."
A statement by the Central Government Liaison Office in Hong Kong said violent protests in the city should not be tolerated in any civilised society, and it was wrong for US politicians to "beautify their terror acts".
"We call on the US side to immediately stop the dangerous game of playing with fire and going further down the wrong path, otherwise it will suffer bad consequences," it said.
The National People's Congress Foreign Affairs Committee and Chinese People's Political Consultative Conference Foreign Affairs Committee also condemned the bill.
More than 1,200 US companies do business in Hong Kong, of which more than 800 are either regional offices or headquarters, attracted by the city's free market orientation, transparent legal system and well-established rule of law, according to the American Chamber of Commerce in Hong Kong.
Additional reporting by Robert Delaney
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