China has tightened its rules on the export of rare earths - the elements that are crucial to the manufacture of many high-tech products, BBC reports.
New regulations announced by the country's Ministry of Commerce "to safeguard national security" formalise existing rules on processing technology and unauthorised overseas cooperation.
China is also likely to block exports to foreign arms manufacturers and some semiconductor firms.
Rare earth exports are a key sticking point in the months-long negotiations between Beijing and Washington over trade and tariffs. The announcement comes as China's President Xi Jinping and his US counterpart Donald Trump are expected to meet later this month.
Technology used to mine and process rare earths, or to make magnets from rare earths, can only be exported with permission from the government, the Ministry of Commerce said.
Many of these technologies are already restricted. China had added several rare earths and related material to its export control list in April, which caused a major shortage back then.
But the new announcement makes clear that licenses are unlikely to be issued to arms manufacturers and certain companies in the chip industry.
Chinese firms are also banned from working with foreign companies on rare earths without government permission.
China has been accused by the US and other Western countries of aiding Russia's war on Ukraine by allowing dual technology exports - materials that can be used for either civilian or military purposes - to be sent to Moscow. Beijing has repeatedly denied this.
The latest announcement also clarifies the specific technologies and processes that are restricted.
These include mining, smelting and separation, magnetic material manufacturing, and recycling rare earths from other resources.
The assembly, debugging, maintenance, repair, and upgrading of production equipment are also prohibited from export without permission, the announcement added.
This could have an impact on the US, which has a significant rare earths mining industry but lacks processing facilities.
bd-pratidin/GR
