The Government Accountability Office report is to be released Monday, The Washington Post reported.

The report is based on an investigation that used undercover staffers. They found that 20 percent of the 184 branch banks they visited did not provide lists of fees and interest rates, and half the 154 financial institutions did not give the details on their Web sites.

Eric Halperin, director of the Center for Responsible Lending, said banks have turned overdraft and other fees into a revenue source. One method is to cover debit card transactions when customers do not have the money in their accounts and then charge for the service.

"Most people think their debit card is a safe way to do transactions because it's not like your credit card -- you can't spend money you don't have," he said. "But actually, banks have turned that on their head and are turning people's debit cards into credit cards with interest rates that are astronomical."