A US State Department spokeswoman says the country holds grave concerns about legal changes allowing suspects in Hong Kong to be extradited to mainland China.
The United States is gravely concerned about proposed amendments to Hong Kong laws that would allow suspects to be extradited to mainland China, a US State Department spokeswoman says.
Morgan Ortagus told a regular news briefing that "the continued erosion of the 'one country, two systems' framework puts at risk Hong Kong's long-established special status in international affairs".
Ortagus said a peaceful demonstration on Sunday by hundreds of thousands of people in Hong Kong "clearly shows the public's opposition to the proposed amendments".
"The US shares the concern of many in Hong Kong that the lack of procedural protection in the proposed amendments could undermine Hong Kong's autonomy and negatively impact the territory's longstanding protections of human rights, fundamental freedoms and democratic values," she said on Monday.
Ortagus said the US was concerned that the amendments could damage Hong Kong's business environment "and subject our citizens residing in or visiting Hong Kong to China's capricious judicial system".
"Any amendments to the fugitive offenders ordnance should be pursued with great care and in full consultation with a broad range of local and international stakeholders who may be affected by the amendments," she said.
Hong Kong leader Carrie Lam vowed on Monday to push ahead with the amendments despite the city's biggest protest since its handover from British to Chinese rule in 1997.
Britain handed Hong Kong back to China under a "one country, two systems" formula with guarantees that its autonomy and freedoms, including an independent justice system, would be protected.
But many accuse China of extensive meddling in many sectors, denying democratic reforms and squeezing freedoms.
A 1992 US law recognises Hong Kong's special status and allows the United States to engage with it as a non-sovereign entity distinct from China in matters of trade and economics.
Areas of special treatment include visas, law enforcement, including extraditions, and investment.
A US congressional commission said last month that amending the law could provide grounds for Washington to re-examine elements of its relationship with Hong Kong outlined in the 1992 law.