ABC Online; The Australian Consumers Association (ACA) is calling for an investigation into bank fees, some of which it says could be illegal.
The ACA's Gordon Renouf says it is not clear whether financial institutions are charging penalties to recoup losses for processing matters, such as late payments or bounced cheques.
Mr Renouf says government and regulators have not forced financial institutions to reveal what proportion of the banks' penalty revenue is cost recovery and what is profit.
He says it is illegal for banks to charge more than it costs to recover losses.
"The fees are imposed because consumers don't comply with their contracts, for example, by having not funds available for a direct debit or overspending on their credit card, or not paying on time," he said.
"You're entitled to charge the cost that has been incurred and not some greater amount to make a profit."
The Australian Bankers Association (ABA) has rejected the claims.
ABA chief executive David Bell says financial institutions already provide enough information about late fees.
"Banks are required by law, by black letter law to disclose the information. We do that," he said.
"In addition we actually agree with the Consumers Association, when we say that fees are avoidable.
"Banks and the ABA have produced a number of publications to guide customers down that path."
