The US House of Representatives has approved new Hong Kong-related sanctions, after Beijing imposed a security law that was condemned by countries around the world.
The measure, which was passed unanimously, penalises banks that do business with Chinese officials.
It will have to be approved by the Senate before going to President Trump.
Critics say China’s law ends freedoms that were guaranteed for 50 years when British rule ended in 1997.
“The law is a brutal, sweeping crackdown against the people of Hong Kong, intended to destroy the freedoms they were promised,” said House Speaker Nancy Pelosi.
UK Prime Minister Boris Johnson said the passing of the law was a “clear and serious breach” of the 1985 Sino-British joint declaration.
Under this declaration, Hong Kong was handed back to China in 1997, with certain freedoms guaranteed for at least 50 years under the “one country, two systems” agreement.
The UK has offered residency, and then citizenship, to up to three million Hong Kongers.
But on Thursday China threatened “corresponding measures” to block the citizenship plan.
“If the British side makes unilateral changes to the relevant practice, it will breach its own position and pledges, as well as international law and basic norms,” said the Chinese Embassy in the UK.