US Commerce Secretary Howard Lutnick expressed optimism that concerns surrounding rare earth minerals and magnets "will be resolved" as the deal is implemented.

But the framework will need to be approved by leaders in Washington and Beijing, officials said after a full day of talks at the British capital's historic Lancaster House.

All eyes were on the outcomes of negotiations as both sides try to overcome an impasse over export restrictions, with US officials earlier accusing Beijing of slow-walking approvals for shipments of rare earths.

The world's two biggest economies were also seeking a longer-lasting truce in their escalating tariffs war, with levies reduced temporarily.

"We're moving as quickly as we can," US Trade Representative Jamieson Greer told reporters. "We feel positive about engaging with the Chinese."

Speaking separately to reporters, China International Trade Representative Li Chenggang said: "Our communication has been very professional, rational, in-depth and candid."

Li expressed hope that the progress made in London would help to boost trust on both sides.