China on Friday trimmed its export quota for rare earth resources for the first half of next year.

The country produces more than 95 percent of the world's rare earths, 17 elements critical to manufacturing everything from iPads to low-emission cars.

Beijing imposes production caps and export quotas on the minerals with, it says, the aim of protecting resources and the environment to promote sustainable development.

The restrictions have angered major trading partners and the World Trade Organization has reportedly concluded they are not in line with its rules.

The government will initially allow 27 rare earth producers and distributors to export a total 15,110 tonnes in the first six months of 2014, the Ministry of Commerce said in a statement.

The figure represents a 2.5 percent reduction on the same period this year.

The quota has not always been met. China exported 16,265 tonnes in 2012, according to Customs, just over half the 30,966 tonne quota for the year.