The Ministry of Commerce announced Thursday additional export quotas for rare earth minerals totalling 10,680 tonnes.

Of the added quotas, 9,490 tonnes were light rare earths, and 1,190 tonnes were medium and heavy rare earths, a statement on the MOC website said.

The added quotas would be provided to a total of 12 companies which had recently passed examinations by the Ministry of Environmental Protection, the statement said.

The companies included Baogang Group, the country's largest light rare earth producer, and the Aluminum Corporation of China, the statement said.

The quotas would be addition to the nation's first batch of rare earth export quotas, the statement said.

On December 27 last year, the ministry announced the country's first batch of rare earth export quotas totalling 10,546 tonnes for 11 qualified companies in 2012.

The ministry also noted that companies that had yet to pass the environmental examination would not get the export rights if they failed to meet the second round of environmental examinations before the end of July.

China supplies more than 90 percent of the world's rare earth metals, but its reserves only account for about one-third of the world's total. Faced with widespread environmental challenges, the country has announced production caps, stricter environmental standards and an export quota system for rare earth metals in recent years to protect the environment and preserve the exhaustible resource.