Shanghai's banking watchdog has demanded a thorough investigation into Shanghai's lenders to discover if they received commissions to sell wealth management products promoted illegally by an insurance agency.

Shanghai Fanxin Insurance Agency, the city's largest insurance intermediary, had been selling unauthorized wealth management products, and its former general manager Chen Yi, fled with an alleged 500 million yuan ($81.7 million) of company money but was tracked down and brought back to China earlier this week.

To bring the risk under control, the Shanghai bureau of the China Banking Regulatory Commission has required major Chinese banks in the city to conduct thorough screening to see if they promoted or sold products offered by Fanxin, the department said.

An initial investigation found lenders in the city strictly followed regulators' rules on being commissioned to sell wealth management products, and did not form partnerships with agencies such as Fanxin or sell the company's products.

Very few wealth managers at the banks have been found to have recommended Fanxin's products to private customers, the regulator added, promising punishment for related personnel if they did sell the products.

Industrial Bank, a joint-stock commercial lender headquartered in Fuzhou, Fujian province, denied any links to Fanxin, as it is the focus of the largest scandal to hit China's insurance sector in recent years.

The bank said it never reached a business partnership with Fanxin and had not discovered any of its Shanghai employees had sold Fanxin's products in private.

Last week, the city's insurance watchdog found Fanxin was selling an unauthorized principal-guaranteed wealth management product that promised a yield of 7 to 8 percent. Meanwhile, its general manager, Chen, was inaccessible for weeks and was reported to have fled to Canada with tens of millions of yuan.

On Monday, the Ministry of Public Security said Chinese police tracked her down in Fiji in partnership with international law enforcement officers.

Authorities have yet to make public more details about the scandal, but different sources have described how Chen, 34, rose from a new employee to the real controller of the city's largest insurance agency.