The reserves are mostly in dollars and euros. They top 100pc of GDP in Hong Kong and Singapore, and 50pc in China, Malaysia and Thailand. The BIS said reserve accumulation on this scale distorts the credit system. In China it has led to negative real interest rates and growth of a "shadow banking system" that is hard to control. It causes banks to boost lending beyond safe levels and can "push the expansion of monetary liabilities beyond the ability of the financial system to absorb them".