BEIJING - A Foreign Ministry spokesman defended China's policy adjustment on rare earth exports on Thursday, stating that setting quotas is aimed at protecting the environment.

"China adjusted its export policy entirely for the sake of environmental protection instead of trade distortion or the protection of domestic industries," spokesman Hong Lei said during a regular news briefing.

His comments came in response to a question regarding criticism by the United States of China's rare earth export policy.

The US government announced Wednesday that it has asked the World Trade Organization to make more efforts to settle a trade dispute with China over its export quotas on rare earth metals and other materials.

China has previously discussed the issue with relevant parties, Hong said, adding that the country will set its future quotas in accordance with global market demand and available supplies.

"We hope countries rich in rare earth resources will actively boost the exploitation and production of rare earth," Hong said.

According to a government white paper issued last week, China will implement stricter environmental standards and protective exploitation policies for its rare earth industry.

The country will continue to intensify regulations for the sector while supplying the global market in line with WTO rules, said the white paper.

As a rule, the WTO allows members to take necessary measures to protect their resources and environments. The organization allows export restraints if they are accompanied by simultaneous restrictions over domestic production or consumption.