Beijing has asked its state-owned enterprises to halt US agricultural goods purchases in a fresh blow to US farmers and traders after President Donald Trump further ramped up tariffs on Chinese imports.

Agricultural products, especially soyabeans, have been at the centre of the escalating US-China trade war, with the US insisting that China must make substantial purchases of the crop as part of any trade deal.

Before the trade war began, China was the largest importer of US soyabeans, buying 25m-30m tonnes a year. However shipments have plummeted: since the start of the crop year in September it has agreed to buy only 14m tonnes, of which 10m has been shipped, according to official US data. The US delivered just 5.3m tonnes of soyabeans to China in the first five months of this year, against 15.2m tonnes in the first five months of 2018.