US rare earth companies jumped in premarket trading as China tightens rare earth export controls. USAR rose 8%; CRML up 7%; MP and NB up 6%; UAMY rose 5%; UUUU rose 4%.

China tightened its rare earth export controls on Thursday, expanding restrictions on processing technology, unauthorised overseas cooperation and spelling out its intention to limit exports to overseas defence and semiconductor users.

Exports of technology used to mine and process rare earths or make the associated magnets is barred without permission, the Ministry of Commerce said in a statement. Many of these technologies are already restricted and it was not immediately clear what the new rules will add.

China added several rare earths and related material to its export control list in April, however Thursday's announcement explicitly said licenses are unlikely to be granted for defence companies as well as certain users in the semiconductor sector.

Chinese companies are also barred from working with companies overseas on rare earths without permission from the ministry.