It makes sense for China to diversify its huge stockpile of foreign exchange reserves, the U.S. Treasury's economic and financial emissary to China said on Friday.

China's forex reserves, the world's biggest stockpile, stood at $2.13 trillion at the end of June.

China has expressed concerns in the past about the value of its holdings of U.S. Treasuries, as massive U.S. debt offerings pose the risk of eroding the value of dollar assets.

The general issue is that China has a huge amount of reserves and it makes some sense to diversify what you put these reserves (into), David Dollar told a meeting of the World Economic Forum in the northeast Chinese city of Dalian.

It's healthy to have a wide and different type of reserve currencies, he said.

The composition of China's foreign exchange reserves is a state secret. Analysts estimate that up to 70 percent of the stockpile is invested in dollar-denominated assets, mainly in U.S. government debt.

Dollar ran the World Bank's Beijing office until earlier this summer.

(Reporting by Eadie Chen and Jason Subler; Editing by Ken Wills)