President Donald Trump has accused China of “letting us down” by not promptly buying more US farm products.

“They have not been buying the agricultural products from our great Farmers that they said they would,” the president said on Twitter on Thursday. “Hopefully, they will start soon.”

After meeting with President Xi Jinping late last month, Trump said China had agreed to buy more US agricultural products as part of a ceasefire in the two countries’ trade war.

The truce suspended US plans to impose tariffs on an additional $US300 billion ($A430 billion) in Chinese goods – action that would have extended the taxes to everything China ships to America.

The US and China are sparring over the Trump administration’s allegations that Beijing is using predatory tactics, including stealing sensitive technology and forcing US firms to hand over trade secrets, to try to supplant American technological supremacy.

Trump has imposed 25 per cent tariffs on $US250 billion in Chinese imports. Beijing has counterpunched by taxing $US110 billion in US goods, specifically targeting US farm products produced by many Trump supporters in the US heartland.

The administration has rolled out $US27 billion in aid to farmers to ease the pain.

Trump and Xi agreed to restart negotiations that had broken down in May after 11 rounds of talks. So far, the two countries’ top envoys have spoken by phone but haven’t announced plans to resume face-to-face talks.

In addition to opposing sharp-elbowed Chinese tech policies, the US wants Beijing to buy more US products and to narrow America’s trade deficit with China – a record $US381 billion last year.

Last month, a former Chinese diplomat, Zhao Weiping, told reporters in New York that the US was asking “us to purchase more than we can buy”. He added, “You have to be realistic.”

Still, Larry Kudlow, director of Trump’s National Economic Council, said on Thursday that “our side expects China very soon to start purchasing American agriculture commodities, crops, goods and services”.