The spat between China and Japan about supplies of so-called rare earth minerals – vital commodities used in high-tech goods from computers to electric cars – is more than just a diplomatic clash.

Driving the dispute is Beijing’s ambition to use tough export limits on these commodities as leverage to encourage foreign companies to relocate production lines to China.

Global concerns about China’s dominance of rare earth production have grown rapidly following, what Tokyo says, has been a near halt to shipments to Japan. Purchasers in Europe and the US say they are still getting shipments, albeit slowly. Each side tells a different version of the story: Beijing has officially denied the embargo to Japan and says heavy export quota cuts, imposed earlier this year, mark an effort to conserve resources.