The Treasury said in its report the yuan had risen in value by 9.7 percent since June 2010, and by 12.6 percent when inflation is taken into account. China's trade and current account surpluses have both fallen to 2.6 percent of gross domestic product from peaks of 8.8 and 10.1 percent respectively of GDP, it said.
"The Chinese authorities have substantially reduced the level of official intervention in exchange markets since the third quarter of 2011, and China has taken a series of steps to liberalize controls on capital movements, as part of a broader plan to move to a more flexible exchange rate regime," the report said.
Still, the Treasury said the yuan remained significantly undervalued. It vowed to keep pressing China to let its currency rise further to "level the playing field for American workers and businesses and support a strong, sustainable and balanced global economy."
The US trade deficit with China reached US$29.1 billion in September. It is running 6.8 percent ahead of last year's record pace. It has long been the largest US trade gap with any one country.
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