The US has filed a fourth WTO complaint against China over import restrictions on copyright-protected products, having failed to resolve the dispute through bilateral discussions, AFP reported. The complaint, which alleges that Beijing unfairly blocks films, music and books from entering the country, is now set to be heard by a WTO dispute resolution panel. Central to the dispute is the Chinese legal requirement that such copyright-protected products be imported through state-approved or state-run companies rather than through US companies. Washington claims that Beijing promised to ease these restrictions as a condition of it joining the WTO. The US has previously called for a dispute resolution panel to examine China's record on import barriers on autos and auto parts, industrial subsidy programs and intellectual property rights protection. It normally takes years for the WTO to deal with such complaints.