BEIJING — China’s Ministry of Commerce has started issuing more export licenses for shipments of rare earth magnets this week, but the pace remains slow and China appears committed to the licensing requirements introduced two months ago.

Many factories in the automotive sector and other industries in Europe and the United States, and a few in Japan, are running low on the magnets. China makes 90% of the world’s supply of these magnets, which are essential for cars, drones, factory robots, missiles and many other technologies.

After a lengthy call on Thursday with Xi Jinping, China’s top leader, President Donald Trump wrote on social media that the two men had discussed rare earths. Trump mentioned that rare earths were a complex subject but did not indicate whether anything had been decided about China’s strict export licensing requirement, which Beijing imposed on April 4.

The presidents agreed that their senior aides would meet soon for further discussions.

China’s statement about the call did not mention rare earths. Lin Jian, a spokesperson for China’s foreign ministry, declined to answer a question about the minerals Friday at the ministry’s daily briefing, saying that it was a matter for other agencies. Thursday, the Ministry of Commerce said only that it would issue export licenses according to its new rules.

The U.S. and European chambers of commerce in China each said Friday that somewhat more export licenses had been issued in recent days. But both groups emphasized that more were needed, as the Ministry of Commerce faces a huge backlog of detailed applications for licenses.

Rare earth metals, a group of 17 elements found near the bottom of the periodic table, have a wide range of industrial applications. China produces practically the entire world’s supply of seven of the least common rare earths, including three that are crucial in making powerful, heat-resistant magnets.

On April 4, two days after Trump sharply increased tariffs on imports from China, China banned all exports except those approved by licenses for the seven rare earths and magnets made from them.

Jin Canrong, a professor of international relations at Renmin University in Beijing and an influential adviser to the Chinese government, said China did not appear to have made any concessions on rare earth supplies during or after the conversation between Trump and Xi.