Donald Trump's latest threat to impose an additional 100% tariff on Chinese goods is 'a typical example of US double standards', China's government has said.

A commerce ministry spokesperson also said China could introduce its own unspecified 'countermeasures' if the US president carries out his threat, adding it was 'not afraid' of a possible trade war.

On Friday, Trump hit back at Beijing's move to tighten its rules for rare earths exports, accusing it of 'becoming very hostile' and trying to hold the world 'captive'. He also threatened to pull out of a meeting with China's President Xi Jinping later this month.

But on Sunday, Trump wrote: 'Don't worry about China, it will all be fine!'

Highly respected President Xi just had a bad moment. He doesn't want Depression for his country, and neither do I. The U.S.A. wants to help China, not hurt it!!! Trump said in a social media post.

Trump's comments rattled financial markets, with the S&P 500 share index closing down 2.7%, its steepest fall since April.

China's response echoes the language from the peak of the recent trade conflict, criticising US export restrictions on chips while defending its own export controls as necessary for national security. The spokesperson reiterated that 'resorting to tariff threats is not the right way to engage with China' and affirmed that the country is prepared for a tariff war if necessary.

This tension follows China's announcement of tighter export controls on vital materials, critical for advanced technology manufacturing, raising concerns over potential disruptions in global supply chains.

Negotiations are anticipated between the two leaders at an upcoming summit, but uncertainty remains over the future of trade relations amidst escalating posturing.