(BSS/AFP) - China announced further controls Thursday on the export of rare-earth technologies and items, adding to existing regulations on the critical industry.

Rare earths have represented a major sticking point in recent trade negotiations between China and the United States, with Washington accusing Beijing of slow-walking export licence approvals.

China is the world`s leading producer of the vital minerals used to make magnets that are essential to the automotive, electronics and defence industries.

The new controls -- which kick in immediately -- mean exporters must obtain permission for technologies used for rare-earth mining and smelting, among other processing steps, a Chinese commerce ministry statement said.

They will also apply to technologies used in the "assembly, adjusting, maintenance, repair and upgrading of production lines", it said.

In another announcement, the commerce ministry said there would be additional restrictions placed on foreign entities that export related items outside of China.

"For some time, some overseas organisations and individuals have directly or after processing transferred or provided controlled rare-earth items originating in China... for direct or indirect use in sensitive areas such as military operations," a ministry spokesperson said in a separate statement.

The practice has caused "significant damage or potential threats to China`s national security and interests (and) adversely impacted international peace and stability", the statement said.