Trade negotiators from China and the United States worked to resolve a number of thorny issues yesterday in Beijing, with talks expected to continue today.

The talks, initially planned for two days, began on Monday. This is the first time the two sides have met face to face since their respective presidents met in Argentina last December.

US President Donald Trump expressed optimism yesterday, tweeting: "Talks with China are going very well!"

Chinese Vice-Premier Liu He, who is Mr Xi Jinping's top economic adviser, made a surprise appearance at the negotiations on Monday in a sign the Chinese were also pushing for a positive outcome.

The Chinese Foreign Ministry said yesterday that Beijing would release a statement after the talks concluded, but did not give a timing.

Since the two presidents met on Dec 1, China has made a number of concessions to US demands, including temporarily cutting punitive tariffs on US-made cars, resuming soya bean purchases, promising to open up its markets for more foreign investment, and drafting a law to prevent forced technology transfers.

Yesterday, China also approved five genetically modified crops from the US for import, the first time it has done so in about 18 months.

Without a resolution to the dispute, US duty rates on US$200 billion (S$271.8 billion) in Chinese goods are due to rise to 25 per cent from 10 per cent on March 2.