China has denounced US President Donald Trump’s threat of new tariffs on $US200 billion ($A270 billion) of Chinese goods as blackmail, warning it will respond with “strong countermeasures”.

On Monday, Mr Trump ordered the US Trade Representative to prepare new tariffs on Chinese goods, escalating a dispute over Beijing’s technology policy that companies and investors worry could drag down global trade and economic growth.

In response, the Commerce Ministry warned Beijing was ready to “defend the interests of the Chinese people and enterprises”, but gave no details.

“This practice of extreme pressure and blackmail deviates from the consensus reached by two parties through many negotiations, and it also disappointed the international community,” the forcefully worded statement said.

“If the US side becomes irrational and issues the list, China will have to adopt measures that are comprehensive measures in quantity and quality in order to make strong countermeasures.”

China has already slapped tariffs on soybeans imported from the US. Photo: AAP

On Saturday, Beijing announced it was imposing 25 per cent tariffs on $US34 billion ($A46 billion) of US imports, including soybeans and beef. The tariffs are effective from July 6 and are in response to measures imposed by Mr Trump on a similar amount of Chinese goods.

The ministry said it would also scrap deals made with Washington to narrow China’s politically volatile trade surplus with the US by purchasing more American farm goods, natural gas and other products.

The US and China have the world’s biggest trading relationship but official ties are increasingly strained amid complaints Beijing’s industry development tactics violate its free-trade pledges and hurt American companies.

Europe, Japan and other trading partners raise similar complaints, but Mr Trump has been unusually direct about challenging Beijing and threatening to disrupt such a large volume of exports.

-AAP