Yuan won't be major reserve currency-China adviser

* Dollar will stay key reserve currency -PBOC academic member

* Says yuan may account for 3-5 pct of global reserves in 10 yrs

* Says Beijing should stick to managed currency regime

BEIJING, Aug 3 (Reuters) - The yuan may only account for 3 to 5 percent of global reserve currencies a decade from now, an advisor to China's central bank said on Wednesday, in remarks that underscored the global importance of the dollar as an investment.

Writing at a time of global concerns over U.S. economic health, Xia Bin, an academic member on the monetary policy committee of the People's Bank of China, said the dollar would remain an important reserve currency for a long time yet.

"The dollar will serve as the most important world reserve currency for a quite long time in the future," Xia said in an article published in the China Finance magazine.

Confidence in the dollar and the U.S. economy has taken a beating after the United States narrowly escaped a disastrous debt default this week, running the risk of losing its gold-plated credit rating.

Xia's prediction for the yuan's future contrasts with others in China who, worried about the dollar's prospects, have called for alternative reserve currencies, including the yuan.

Xia did not elaborate on why he thought the yuan would not grow into a major reserve currency, but made clear that Beijing should stick to its present model of a managed floating currency regime to shield its economy from risks.

Without giving details, he said China should not have a free float currency regime in the next 10 years, and that while its capital account must be freed to make the yuan convertible, capital controls should only be loosened gradually.

"In the coming eight to nine years, China would be forced to continue with a managed float of its exchange rate in the face of reform challenges in its economy and global financial uncertainties," he said

"Reforms in the foreign exchange rate, capital account management and other domestic policies should be well coordinated to avoid destabilising the economy," he said.

It was not clear if Xia's comments reflected official thinking in Beijing. While advisers to China's central banks occasionally act as the bank's mouthpiece, it is not always the case. (Reporting by Aileen Wang and Koh Gui Qing; Editing by John Stonestreet)