Charlene Chu, head of Chinese banks’ ratings at Fitch, said: "Managing WMP issuance and payouts is becoming a growing logistical challenge. Add to this poor disclosure plus the fact that many of the assets and liabilities spend much of their life off-balance sheet and there is clearly cause for concern."

The difference between WMPs and time deposits is that in WMPs, the interest rates can be set freely by banks and many of the assets and liabilities stay off the balance sheets.

These products issued by Chinese commercial lenders usually require a minimum investment of CNY50,000, and the capital from buyers often goes into bonds, loans, and company projects.

Further, Fitch Ratings added that the nominal amount of outstanding WMPs rose to CNY12 trillion in the third quarter, and could surpass CNY13 trillion by year-end, in contrast to the CNY8.5 trillion in 2011.

And in the recent years, the issuance has been driven mainly by non-state banks, with more than 85% of the CNY3.5 trillion net increase in the first nine months taking place among joint-stock and city and rural commercial banks, Fitch said.

By the end of the third quarter, Chinese banks were found to be issuing the equivalent of 100 new WMPs per day and Fitch revealed that the turnover is high with approximately three-fourths of products maturing within six months.

"The opacity surrounding wealth-management products remains a concern," Fitch said.