According to the Critical Raw Materials Alliance, China produces about 80 per cent of the world's gallium and about 60 per cent of germanium.

However, the country didn't sell any elements on international markets last month. In July, the country exported 5.15 metric tons of forged gallium products and 8.1 metric tons of forged germanium products.

China's commerce ministry said it had received applications from companies to export the two materials, but only “some applications” had been approved.

The curbs indicate China's apparent willingness to retaliate against US export controls despite concerns about economic growth.

For those who came in late, the US has stopped the Chinese from buying high-end tech, citing “security concerns” when it mostly appears to be to prop up US chip developers. However, with China refusing to export these rare materials, US chip developers will find themselves in a supply shortage.