The restatement of Governor Zhou Xiaochuan's proposal in March added to speculation that China will diversify its currency reserves, the world's largest at $1.95 trillion at the end of March. Chinese investors, the biggest foreign holders of U.S. Treasuries, reduced holdings in April after Premier Wen Jiabao expressed concern about the value of dollar assets.

"Zhou Xiaochuan sees the current international financial system is flawed, putting too much emphasis on the dollar as a reserve currency," said Kevin Lai, an economist with Daiwa Institute of Research in Hong Kong. "The dollar should depreciate to address the global imbalance but because it’s a reserve currency it cannot."

President Barack Obama needs the support of China as the U.S. tries to spend its way out of recession. The Dollar Index that measures the currency's performance against six trading partners fell as much as 0.7 percent at 12:42 p.m. in London.

China, the biggest foreign holder of U.S. government, cut its holdings by $4.4 billion to $763.5 billion in April, the first monthly reduction since February 2008, according to U.S. Treasury Department data. At the end of 2008 the dollar accounted for 64 percent of global central bank reserves, down from 73 percent in 2001, according to the IMF in Washington.

"There may be signs here of tensions mounting between the PBOC's economic concerns over China's holdings of dollars and the Chinese government's diplomatic reasons for doing so," Stephen Gallo, head of market analysis at Schneider Foreign Exchange in London, wrote in an e-mail.

Russian President Dmitry Medvedev, Chinese President Hu Jintao, Indian Prime Minister Manmohan Singh and Brazilian President Luiz Inacio Lula da Silva called for a "more diversified" monetary system to reduce dependency on the greenback at a June 16 meeting in the Russian city of Yekaterinburg. In May, China and Brazil began studying a proposal to move away from the dollar and use yuan and reais to settle trade instead.

Group of 20 leaders on April 2 gave approval for the IMF to raise $250 billion by issuing Special Drawing Rights, or SDRs, the artificial currency that the agency uses to settle accounts among its member nations. It also agreed to put another $500 billion into the IMF's war chest. This month, Russia and Brazil announced plans to buy $20 billion IMF bonds, while China said it is considering purchasing $50 billion.

"Special drawing rights of the IMF should be given full play, and the international body should manage part of its members' reserves," the central bank report said.

IMF First Deputy Managing Director John Lipsky said on June 6 it's possible to take the "revolutionary" step of making SDRs a reserve currency over time.

SDRs were created by the IMF in 1969 to support the Bretton Woods exchange-rate system that collapsed in 1971. They act as a unit of account rather than a currency. The cash is disbursed in proportion to the money each member nation pays into the fund.

The value of SDRs are based on a basket of currencies, shielding them from swings in a single currency. One SDR is valued at $1.54. China is proposing the basket be broadened. The current weighting is: 44 percent for the dollar, 34 percent for the euro and 11 percent each for the yen and the pound. It doesn't include the yuan.

The dollar's dominance of global finance buffeted developing nations last year. Investors abandoned emerging markets after the September bankruptcy of Lehman Brothers Holdings Inc. eliminated demand for all but the safest, most easily traded assets, such as Treasuries and the dollar. A shortage of the U.S. currency forced central banks to pump reserves into their economies.

"The excessive reliance on the credit of several sovereign currencies have added to the extent of risks and crises," the central bank report said. "A currency with stable value in the long term is required."