China on Tuesday expressed firm opposition to the US Senate\'\'s bill on the Chinese yuan, after it voted to allow a debate on the so-called \"currency manipulation\" bill. Such a move \"seriously violates rules of the World Trade Organization and obstructs China - US trade ties,\" Foreign Ministry spokesman Ma Zhaoxu said in a statement. China urges certain U.S. Senators to \"rationally understand Sino-US trade cooperation, which is mutually beneficial in nature, and stop pressuring China through domestic law-making,\" he said. The bill \"will further escalate the exchange rate issue by adopting protectionist measures with an excuse of \'\'currency imbalance,\'\'\" he said. \"China - US economic and trade cooperation, which has brought concrete interests of Chinese and American peoples, has a protruding feature of mutual benefits and win-win results and thus has become an important foundation and driving force of Sino-US ties,\" Ma said. Statistics indicate that China and the U.S. are each\'\'s second largest trading partners, and China is the fastest-growing export market. \"It is widely understood that the exchange rate of the renminbi, the Chinese currency, is not the cause of the Sino-U.S. trade imbalance,\" Ma pointed out. The yuan has appreciated 7 percent against the U.S. dollar since June 2010, when the central bank announced further yuan exchange rate formation mechanisms. China will continue to institute a managed floating exchange rate system, reported China Xinhua News Agency. China calls on the United States to abandon protectionism or politicizing economic issues so as to create favorable environment for the growth of bilateral economic and trade ties, he said. The U.S. Senate voted Monday (local time) to allow a debate on the bill that addresses so-called \"currency manipulation\" by China amid strong opposition from China and U.S. business groups.(