China’s banking regulator chief warned that a “black swan”, or an unforeseen event could threaten the country’s financial stability, official People’s Daily reported on Wednesday.

In an interview with the paper, Guo Shuqing said that while risks in the financial system are manageable, they are still “complex and serious.”

Since his appointment as the head of the China Banking Regulatory Commission early last year, Guo has introduced a flurry of new rules to reign in lender risks including from curbs on shadow banking activities to the crackdown on loan fraud.

Guo said the dangers stem from the pressure of rising bad debt, imperfect internal risk systems at financial institutions, the relatively high levels of shadow banking activities and rule violations.

All of these risks could upend financial stability through a “black swan” event, Guo told the People’s Daily, referring to major, unexpected occurrences.

“We need to focus on reducing the debt ratio of companies, restrict household leverage, strictly control cross-financial sector products, continue to dismantle shadow banking,” said Guo.

China will step up oversight of the banking sector this year to reduce financial risks, the CBRC said on Monday, stressing that long-term efforts would be needed to control banking sector chaos.