Four major automakers are racing to find workarounds to China’s stranglehold on rare-earth magnets, which they fear could force them to shut down some car production within weeks.Several traditional and electric-vehicle makers—and their suppliers—are considering shifting some auto-parts manufacturing to China to avoid looming factory shutdowns,

Sefcovic’s comments echo concerns raised by other government officials including those in the Trump administration, which has accused China of breaking a deal reached in Geneva last month to, among other things, lower barriers for exports of rare earth materials.

China has introduced a tracking system for its rare earth magnet sector, three sources said, as its export restrictions on them begin to cut off customers around the world. The national tracking system,