The United States and China are close to finalising some sections of a trade agreement after a phone call between top negotiators, the US Trade Representative's office has said.

"They made headway on specific issues and the two sides are close to finalising some sections of the agreement," USTR said after a phone call on the initial phase of the agreement between Chinese Vice Premier Liu He, US Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin.

"Discussions will go on continuously at the deputy level, and the principals will have another call in the near future."

Top US and Chinese trade officials discussed plans for China to buy more US farm products, but in return, Beijing will request cancellation of some planned and existing US tariffs on Chinese imports, people briefed on the talks told Reuters.

The two sides are working to try to agree on a text for a "Phase 1" trade agreement announced by US President Donald Trump on 11 October, in time for him to sign it with China's President Xi Jinping next month at a summit in Chile.

So far, Trump has only agreed to cancel a 15 October increase in tariffs on $250 billion in Chinese goods as part of understandings reached on agricultural purchases, increased access to China's financial services markets, improved protections for intellectual property rights and a currency pact.

But to seal the deal, Beijing is expected to ask Washington to drop its plan to impose tariffs on $156 billion worth of Chinese goods, including mobile phones, laptop computers and toys, on 15 December, two US-based sources told Reuters.

Beijing also is likely to seek removal of 15% tariffs imposed on 1 September on about $125 billion of Chinese goods, one of the sources said.

Trump imposed the tariffs in August after a failed round of talks, effectively setting up punitive duties on nearly all of the $550 billion in US imports from China.