President Donald Trump asked Chinese leader Xi Jinping whether Beijing would like to buy American weapons, according to a report that has raised eyebrows in Washington.

The remarkable exchange was reported by NPR, which said Trump raised the idea during recent contacts between the two leaders.

The US State Department moved quickly to shut down the suggestion, saying American law prohibits such sales to China and that no offer or plan exists.

Arms sales to China have been banned under US law since the 1989 Tiananmen Square crackdown, and any change would require an act of Congress. The ban is one of the longest-standing pillars of American policy towards Beijing.

The report underlines the unusual nature of the current US-China relationship, where trade talks and strategic rivalry run in parallel. Beijing has not publicly commented on the claim, and analysts cautioned against reading too much into what may have been an offhand remark.