China lost an appeal at the World Trade Organization in a case brought by the United States, the European Union and Japan to challenge China's restrictions on exports of rare earths, according to a WTO Appellate Body ruling published on Thursday. "... China has not demonstrated that the export quotas that China applies to various forms of rare earths, tungsten and molybdenum by virtue of the series of measures at issue are justified ... " the document's conclusion said. China produces more than 90 percent of the world's rare earths, which are key elements in defence industry components and modern technology from iPhones and disk drives to wind turbines. It imposed strict export quotas in 2010, saying it was trying to curtail pollution and preserve resources.