US and Chinese negotiators met for a fifth straight day on Sunday, as the two sides race against a 1 March deadline to reach agreement and prevent a further trade war escalation.

The fourth round of negotiations between the world's two biggest economies was extended through the weekend after both sides reported progress in narrowing differences.

President Donald Trump said on Friday that there was "a very good chance" a deal would be struck, and that he was inclined to extend his tariff deadline beyond 1 March and meet soon with Chinese President Xi Jinping.

Extending the deadline would mean putting on hold a scheduled increase to 25 per cent from 10 per cent on $US200 billion of Chinese imports into the US.

That would prevent any worsening of a trade war that has already disrupted commerce worth hundreds of billions of dollars of goods, slowed global economic growth and roiled markets.

US markets have ticked up in anticipation of a new deal and dovish signals from the US Federal Reserve, which has abandoned - or at least delayed - its program of interest rate rises.

The New York Stock Exchange has gained 18 per cent since the December sell-off, as all major indices rebounded. Both the Dow and Nasdaq marked a ninth week of consecutive increases when they closed last Friday.

Australian investors are also closely watching negotiations, given China accounts for around 38 per cent of our total exports. 

Outside of trade, inbound tourism from China is also a major contributor to Australia's economy. Some 1.3 million Chinese visited Australia last year, accounting for more than 15 per cent of total visitors, and spent $11.5 billion, research from Tourism Research Australia shows.

Trump Xi Jinping

Australian markets are also closely watching the Trump, Xi Jinping trade talks

Narrowing differences between Trump, Xi Jinping

Trump and US Treasury Secretary Steven Mnuchin said the two sides had reached an agreement on currency issues, but did not give details.

US officials have long argued that China's yuan is undervalued, giving China a trade advantage and partly offsetting US tariffs.

China has also committed to buy an additional 10 million metric tons of US soybeans.

An industry source briefed on the talks said both sides have narrowed differences on intellectual property rights, market access and narrowing a nearly $US400 billion US trade deficit with China.

But bigger differences remain on changes to China's treatment of state-owned enterprises, subsidies, forced technology transfers and cyber theft.

There is no agreement on the enforcement mechanism either. The US wants a strong mechanism to ensure the Chinese reform commitments are followed through, while Beijing insists upon what it calls a "fair and objective" process.

"Enforcement is a difficult puzzle," said the source, who requested anonymity to speak candidly about the talks. "You need objective arbitrators to make a decision."

Trump said the biggest decisions could be reached when he meets with Xi, probably in Florida next month, and that they may extend beyond trade to encompass Chinese telecommunications companies Huawei Technologies and ZTE Corp.