Britain's biggest banks will appeal against the findings of a High Court test case on penalty charges, in an attempt to stop an Office of Fair Trading (OFT) investigation that could cost them billions of pounds.

Today, eight high street banks, including Barclays, HSBC and Royal Bank of Scotland, will seek permission to appeal against a High Court judgment allowing the OFT to press ahead with an investigation to determine whether bank charges are unfair.

The appeal will cause disappointment for hundreds of thousands of customers who are trying to reclaim penalty fees after going overdrawn or missing payments.

The Financial Services Authority (FSA) has granted the banks permission to put claims on hold until the judicial process is completed. Tens of thousands more cases initiated in the county courts or with the Financial Ombudsman Service have also been suspended, pending a final judgment.

Phil Jones of Which?, the consumer organisation, said: “The banks should stop stringing this out. The charges are seen as unfair by consumers so they should do the decent thing and pay compensation to those who have made a claim and reduce the fees to a fair level.”

However, as the banks struggle with their own financial problems, analysts say that they are not going to accept a judgment that could lead to customers reclaiming billions of pounds.

The banks are concerned that if the OFT is allowed to proceed, it could cap the fee for bouncing cheques or exceeding overdraft limits at a far lower rate than the £30 typically charged.

It could even force banks to refund the difference between the charges they imposed and a new acceptable rate of penalties set by the regulator.

Analysts estimate that a cap on overdraft charges could cost the banks £10billion in lost revenue and force the end of free banking.

The OFT has not announced whether it believes that the current level of overdraft charges is unfair, or what a fairer amount would be.

However, analysts point to a previous OFT ruling on credit card fees that forced the banks to cut charges from up to £35 to £12 as an indication of which way it is likely to go.

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