(Reuters) -China has quietly issued its first 2025 rare earth mining and smelting quotas without the typical public statement, sources with knowledge of the matter said this week, another sign of Beijing tightening its control over the crucial sector.

The quotas are closely monitored as a barometer for the global supply of rare earths, a group of 17 elements used in electric vehicles, wind turbines, robots and missiles. China is the world's largest producer of the minerals and the government typically issues them twice a year to state-owned companies but they have been delayed this year.

The government issued the first set of quotas for the year only last month, without the usual public statement, said the sources, with one of them saying the companies were told not to share the numbers for security reasons. These details are being reported here for the first time.

The sources did not give the quota volumes.

China is increasingly sensitive about rare earths and its control over the supply, which it has been willing to assert amid its trade discussions with the U.S. and European Union.

Beijing added several of the elements and related magnets to its export restriction list in retaliation for U.S. tariff hikes, cutting off supply and forcing some automakers outside China to partially shutter production.

In the previous four years, China's Ministry of Industry and Information Technology issued the first batch of quotas in the first quarter of the year in an announcement on its website.

The Ministry did not immediately reply to a request sent by fax for a comment on why the information has not been publicly issued.

Last year, China issued two batches of mining quotas for 270,000 metric tons, with annual supply growth slowing to 5.9% from 21.4% in 2023.

The smelting and separation quota in 2024 was also in two batches, totalling 254,000 tons, up 4.2% from 2023.

Beijing has used the quota system, first introduced in 2006, and corporate consolidation to tame the industry and give officials control over output.

Beijing has narrowed access to the quotas, with only two state-owned groups - China Rare Earth Group and China Northern Rare Earth Group High-Tech - eligible last year, down from six previously.

The quotas were delayed this year partly because of a proposal in February to add imported ore into the quota system, which sparked opposition from companies that rely on imports and were concerned they could lose access to feedstock, according to the two sources and an additional source with knowledge of the matter.