US President Donald Trump signed an order on Tuesday to lower fentanyl-related tariffs on Chinese products, formalising a key part of his deal with President Xi Jinping after their first face-to-face talks in years.

Shortly after returning to the presidency this year, Trump imposed additional tariffs of 20 percent on goods from China over its alleged role in the fentanyl supply chain.

China has since committed efforts to halting the flow of precursors used to make fentanyl into the United States, after Xi and Trump's summit last month in Busan, South Korea.

In turn, Washington pledged that it would cut its additional tariffs on Chinese imports from 20 percent to 10 percent, effective November 10.

Trump's order on Tuesday formalises this agreement, although it said US officials will monitor China's compliance with the deal.

The US president's talks with Xi also yielded a slate of other agreements, including a further suspension of steeper tit-for-tat tariffs until November 10, 2026.

Temperatures have spiked between the world's two biggest economies this year as Washington and Beijing slapped escalating tariffs on each other's products.

At one point, duties on both sides reached prohibitive triple digit levels, hampering trade.

Both countries have been engaged in an uneasy truce since, as top economic leaders met several times for talks in recent months, with tensions surging over export controls and other issues.

But Xi and Trump's meeting has effectively extended their delicate truce for a year. (AFP)