The World Trade Organization opened a formal investigation into allegations that China was providing a safe haven for product piracy and counterfeiting, the most far reaching of four current trade disputes between Washington and Beijing. The United States complaint over China's enforcement of intellectual property rights is the culmination of years of agitation in Washington and elsewhere over one of the world's biggest sources of illegally copied goods, ranging from DVDs, CDs and designer clothes to sporting goods and medications. A United States trade official, Dan Hunter, told the W.T.O's dispute settlement body that while China had taken steps to improve protection and enforcement of property rights, it had not done enough. China criticized the United States this year for starting the case, saying it could damage trade relations between the countries.