Rare earth stocks jumped on Tuesday. American Resources up 39%; Critical Metals up 21%; Energy Fuels up 5%. Lithium stock Lithium Americas up 10%.

Chinese rare earth magnet companies have been facing tighter scrutiny on export license applications since September, sources say, even before Beijing's move last week to expand controls over the critical minerals used in magnets.

Starting in September obtaining an export license became harder, according to two sources with knowledge of the matter. Applications are now being returned more often with requests for extra information, said one of the sources.

Approvals are taking longer, although generally still within the commerce ministry's 45 business day deadline, said the other, but the scrutiny is now similar to April, at the height of the trade war, when lengthy waits for licenses caused magnet shortages that led to shutdowns at automotive factories.

The sources declined to comment on exactly how much longer it is taking to obtain licenses or elaborate on the questions that are being asked.