China's Central Bank Chief Warns of ‘Sudden, Contagious and Hazardous' Financial Risks

Latent risks are accumulating, including some that are "hidden, complex, sudden, contagious and hazardous," even as the overall health of the financial system remains good, Zhou wrote in a lengthy article published on the People's Bank of China's website late Saturday.

The nation should toughen regulation and let markets serve the real economy better, according to Zhou. The government should also open up markets by relaxing capital controls and reducing restrictions on non-Chinese financial institutions that want to operate on the mainland, he wrote.

"High leverage is the ultimate origin of macro financial vulnerability," wrote Zhou, 69, who is widely expected to retire soon after a record 15-year tenure. "In sectors of the real economy, this is reflected as excessive debt, and in the financial system, this is reflected as credit that has been expanding too quickly."