North China's Inner Mongolia Autonomous Region, China's largest supplier of rare earth minerals, reported a substantial growth in exports as prices fell in the first half of 2015.

Inner Mongolia exported 2,664 tonnes of rare earth products in the first six months, up 36.5 percent year on year, according to local customs.

About half went to the United States and about one third to Japan, up 40 percent and 130 percent respectively.

During the six months, the average export price of rare earth products was 32,000 yuan (5,229 U.S. dollars) per tonne, down 34.7 percent from the same period of last year.

China began to set quotas and high duties on rare earth exports in 2010, causing friction with the European Union, Japan and the United States. Quotas were removed on Jan. 1 this year, and export duties were canceled in May after a WTO ruling in August 2014 declared the measures inconsistent with WTO rules and China's accession protocol.

Rare earth metals are vital for manufacturing high-tech products ranging from smartphones and wind turbines to electric car batteries and missiles.