US President Donald Trump has threatened to impose fresh trade tariffs worth $200 billion on Chinese goods in an attempt to force additional concessions ahead of a critical week of final negotiations between Beijing and Washington to end a year-long tit-for-tat trade war.

Trump has already imposed tariffs on $250 billion worth of Chinese goods and is now threatening to tax nearly all of the products China exports to the US.

In a series of tweets on Sunday, the President warned that he would lift tariffs on Friday on a bundle of Chinese goods to 25 per cent from the current 10 per cent threshold, reactivating a threat he removed months ago just as it appears the two economic super-powers are on their way to a deal, CNN reported.

Trump also warned that he would “shortly” impose levies on hundreds of billions of dollars of additional imports.

He also tweeted that talks between the two nations were progressing “too slowly” and suggested that the Chinese were trying to “renegotiate” the deal.

The renewed tariff threat alarmed investors, sending stock futures down. The Dow was down more than 400 points on Sunday evening, while the Nasdaq was down over 100 points.

The stock market in China opened on Monday more than 3 per cent lower, while shares in Hong Kong were down more than 2 per cent.

The threat caught Chinese officials by surprise. On Monday morning in Beijing, they were trying to decide whether Vice Premier Liu He should go ahead with his visit to Washington on Wednesday, informed sources told The New York Times.

Trump had previously threatened more tariffs, but delayed that increase as he cited “substantial progress” in trade talks, which had moved far enough along that he predicted a signing ceremony with his Chinese counterpart Xi Jinping at some point soon.

The US has been pressing for a pact that would open business opportunities in China for American companies, require China to buy more American goods and end its practice of forcing American firms to hand over valuable technology and trade secrets as a condition of doing business there.

The Chinese, in turn have insisted that Trump drop all of his tariffs before they agree to a deal, a position that has frustrated the President, The New York Times reported.