China furious after Trump signs law backing Hong Kong protesters

China has threatened “firm counter measures” against the United States after President Donald Trump on Thursday signed into law a bill supporting anti-government protesters in Hong Kong.

The Human Rights and Democracy Act requires the State Department to annually certify that Hong Kong retains enough autonomy to justify favourable US trading terms. It also threatens sanctions for human rights violations.

Trump signed the legislation – which comes just as the world's top two economies edge towards a trade truce – under heavy pressure from Congress.

Beijing summoned the US ambassador, warning Washington not to implement the legislation.

"The nature of this is extremely abominable, and harbours absolutely sinister intentions," the Chinese foreign ministry said in a statement.

"China strongly urges the US side to correct mistakes and change course."

Meanwhile Hong Kong's Beijing-backed government said the legislation sent the wrong signal to demonstrators and "clearly interfered" with the city's internal affairs.