China has been secretly increasing its gold reserves.
The BBC reports it was able to keep it secret by buying domestically produced metal, almost doubling the amount of gold it holds to more than 1,000 tons.
China has the biggest foreign exchange reserves in the world, totalling almost $US2,000 billion.
An estimated two-thirds is held in US dollars, though China has been backing away from the dollar as a reserve currency for a while.
Three years ago Beijing broke the link between its currency, the renminbi, and the dollar.
Just before the London G20 summit earlier this month, China suggested that the time might have come for countries to reduce their reliance on the US dollar as a reserve currency.