Critics say the new law effectively ends the 'one country, two systems' framework under which Hong Kong was promised a high degree of autonomy when it reverted from British to Chinese rule in 1997.
Congress has approved a bill rebuking China over its crackdown in Hong Kong amid protests against a strict "national security" law that outlaws so-called subversive or terrorist acts, as well as collusion with foreign forces intervening in the city's affairs.
Critics say the new law effectively ends the "one country, two systems" framework under which Hong Kong was promised a high degree of autonomy when it reverted from British to Chinese rule in 1997.
The U.S. legislation would impose sanctions on groups that undermine Hong Kong's autonomy, including police units that have cracked down on Hong Kong protesters, as well as Chinese Communist Party officials responsible for imposing the new security law. The bill also imposes sanctions on banks that do business with entities found to violate the law.
The Senate gave final legislative approval to the measure on Thursday, a day after the House approved it. It now goes to the White House.
Ahead of the Senate vote, Chinese foreign ministry spokesperson Zhao Lijian said no amount of pressure from external forces could "shake China's determination and will to safeguard national sovereignty and Hong Kong's prosperity and stability".
He urged the US to abide by international law and stop interfering in Hong Kong's affairs, and not sign the sanction bill into law.
If President Donald Trump signs the bill, "China will definitely take strong countermeasures, and all consequences will be borne by the US side," Zhao told reporters on Thursday.
The White House declined to comment, but in a television interview on Thursday, Vice President Mike Pence called the new Hong Kong security law a betrayal of the international agreement China signed.
"President Trump has made it clear that we're going to be modifying our trading relationship and the trading status with regard to Hong Kong and we're going to continue to speak out on behalf of the people of Hong Kong and on behalf of human rights of people within China,” Pence told CNBC.
Sen. Chris Van Hollen, D-Md., a co-sponsor of the Senate bill, said passage of the "Hong Kong Autonomy Act" makes it clear that the United States "will not stand by as China seeks to crush freedom, human rights and democracy in Hong Kong".
The Chinese government "is already flagrantly using their new authorities to punish and imprison those who have stood up against the recent implementation of their sweeping national security law," Van Hollen said.
"Our legislation mandates severe consequences on those who participate in this unconscionable repression."
Sen. Pat Toomey, R-Pa., the bill's other lead sponsor, urged Trump to sign it into law. "With our bill, the CCP will learn there are ramifications for repressing Hong Kongers' freedom," Toomey said, referring to the Chinese Communist Party.
House Speaker Nancy Pelosi also praised the sanctions bill as “an urgently needed response to the cowardly Chinese government's passage of its so-called national security law."
Lawmakers from both parties have urged the Trump administration to take strong action in response to the crackdown by China against the former British territory, which was granted partial sovereignty under a treaty that took effect in 1997.