WASHINGTON: Recent exemptions to sweeping US import tariffs may be short-lived, top officials warned Sunday, as China urged the Trump administration to simply abandon its aggressive trade tax policy altogether.

The world's two largest economies have been locked in a fast-moving, high-stakes game of brinkmanship since US President Donald Trump launched a global tariff assault that particularly targeted Chinese imports.

Tit-for-tat exchanges have seen US levies imposed on China rise to 145 per cent, and Beijing setting a retaliatory 125 per cent band on American imports.

The US side appeared to dial down the pressure slightly on Friday, listing tariff exemptions for smartphones, laptops, semiconductors and other electronic products for which China is a major source.

But Beijing's Commerce Ministry said the move only "represents a small step" and insisted that the Trump administration should "completely cancel" the whole tariff strategy.

The new exemptions will benefit US tech companies like Nvidia and Dell as well as Apple, which makes iPhones and other premium products in China.