HONG KONG -- More than 200 Hong Kong investors marched on 20 local banks Friday to demand a full refund of the money they lost after putting it into financial products backed by failed US giant Lehman Brothers.

The protesters, who said they were mis-sold the products by the banks, complained of being frustrated that little action had been taken by the banks and financial regulators to settle their cases.

A large team of police officers escorted the protesters as they marched along Des Voeux Road, one of the busiest roads in the city's central business hub, stopping at almost every one of the banks.

"You do not have any more credibility. Had it not been your inaction, we would not have taken to the street so many times," Phillip Khan, spokesman for the Alliance of Lehman Brothers Victims, which organized the march, told the bank staff through his loudspeaker.

One of the protesters, Yau Pui-fat, said DBS Bank had not contacted him since September when a staff member told him his investment in Lehman Brothers' structured notes may have become worthless.

"I am hoping they will return me the money. But they do not even bother to call," the 65-year-old told AFP.

Each of the banks they had visited was guarded by staff and security guards at the entrance.

More than 40,000 Hong Kong investors -- including many retirees -- had put a total of 15.7 billion Hong Kong dollars ($2.01 billion) of their savings into mini-bonds and other complex products backed by Lehman Brothers, which filed for bankruptcy in September under mountains of debts.