The Chinese government is tightening controls over exports of two key materials used to make computer chips. BBC News reports that, from next month, special licenses will be needed to export gallium and germanium from China, which is the world's biggest producer of the metals. On July 3, China's Ministry of Commerce said the restrictions were needed to "safeguard national security and interests."

The announcement comes just days before a high-stakes trip to Beijing by U.S. Treasury Secretary Janet Yellen.

The silvery metals are used in semiconductor, communications and military equipment. They are also key materials in products like solar panels.

The U.S. has taken steps to restrict China's access to technology it fears could be put to military use, such as chips used for supercomputing and artificial intelligence. In October 2022, Washington announced that it would require licenses for companies exporting chips to China using U.S. tools or software, no matter where they are made in the world.

The efforts have been joined by countries including the Netherlands and Japan.