"There is pretty broad consensus with the G8 that this is not the time to experiment with reserve currencies, however attractive it might seem," said the source, speaking on condition of anonymity.

G8 sources said earlier this week that China had asked for discussion of proposals for a new global reserve currency at next week's G8 meeting in Italy, which will be expanded on the second day to include China and other emerging nations.

The reserve currency debate centres on proposals by some emerging powers that an alternative should be found to the dollar as the main global reserve currency, to reflect the shifting balance of power in the globalised economy.

China has been particularly vocal. It holds more U.S. Treasury debt than any other country and has expressed fears that Washington's huge spending on economic stimulus could spark inflation, hurting the value of China's dollar-denominated reserves.

(Reporting by Reuters bureaux)