The U.S. will file a complaint at the World Trade Organization today over Chinese limits on exports of rare earths used in high-tech products, deepening a trade dispute between the world's two largest economies.

President Barack Obama will personally announce the action to join Japan and the European Union in requesting consultations with China at the Geneva-based trade arbiter over rare-earths shipments, an administration official said yesterday in Washington, speaking on condition of anonymity ahead of the White House announcement.

The move adds to pressure the U.S. is piling on China in an election year, with Obama calling for efforts to help balance the trade deficit it has with the Asian nation and allow the Chinese currency to appreciate. China produces at least 90 percent of the world's rare earths, used in Boeing Co. helicopter blades and Toyota Motor Corp. hybrid cars, and has curbed output and exports since 2009 to conserve mining resources and protect the environment.