The World Trade Organization has upheld a ruling that China violated international trade rules with restrictions on the export of "rare earths," the minerals used in mobile phones, hybrid cars, flat-screen TVs and other high-tech products.

In March, the WTO dispute settlement panel found that China's restrictions breach WTO rules. Its ruling followed complaints by the United States, the European Union and Japan.

The Geneva-based WTO's appellate panel on Thursday rejected Beijing's appeal, saying it hasn't "demonstrated that the export quotas that China applies to various forms of rare earths ... are justified."

China accounts for more than 90 percent of production of rare earth minerals. In 2009, it alarmed foreign companies by limiting rare earth exports in an attempt to boost its domestic manufacturing base.