Hastening financial reform and a freer pricing mechanism for the renminbi are possible responses to the United States' call for faster appreciation of the Chinese currency, experts said.

In a recent report to the US Congress, the Department of the Treasury said that China, along with other major trading partners, has "not manipulated" the exchange rate between its currency and the dollar.

The same conclusion was reached in the 10 previous reports issued since President Barack Obama took office in 2009.

The report acknowledged measures taken by China this year to loosen capital controls and free up channels for cross-border capital and investment, along with the establishment of the Shanghai free trade zone, which is expected to liberalize interest rates, capital account opening and currency convertibility.

But it insisted that "the renminbi is not appreciating as fast or by as much as is needed".

"The report is correct in that China does not manipulate its currency, but less so about the need for faster yuan appreciation," said He Weiwen, a co-director of the China-US/EU Study Center at the China Association of International Trade.

"Whether a currency is undervalued can only be tested by the market, not by the economic situation of another country," He said.

Although the People's Bank of China, the country's central bank, sets a reference rate for the renminbi on a daily basis, the real exchange rate is now mainly determined by massive renminbi trading in the domestic and offshore markets, he said.

The reference rate of the renminbi against the dollar was 6.1425 on Thursday, the fourth consecutive day that the renminbi had depreciated.

The renminbi has appreciated 12 percent in inflation-adjusted terms against the dollar since June 2010, when China moved off its peg against the dollar, and about 45 percent since China initiated currency reform in 2005.

The range of renminbi appreciation against the dollar was wider than the real effective exchange rate of the renminbi against the currencies of all relative trading partners, which has appreciated about 15 percent since June 2010 and 38 percent since 2005.

Chinese authorities reaffirmed their commitment this year to reforming the exchange rate mechanism.