Encouraged by China's adherence to World Trade Organization rules, more and more US firms are making plans to expand their China activities, a survey by the American Chamber of Commerce has found. According to the report, more than 61% of US businesses said WTO-inspired changes were having a positive impact on their business and were confident that the Chinese leadership fully backed compliance. The result is almost the complete reverse of a similar survey conducted a year earlier. However, respondents also said that piracy remained a major cause of concern with 90% saying enforcement of intellectual property rights laws was ineffective and some three-quarters saying their rights had been infringed.