Mortgage lenders will repay tens of millions of pounds paid by homeowners in “unfair” mortgage exit fees.

Most banks and building societies said yesterday that they would compensate millions of borrowers over exit fees, levied when they moved to a rival lender. They announced their decision in response to a challenge from the Financial Services Authority, which gave them until yesterday to either charge the original exit fees that customers signed up for, or to justify the new, higher fees.

Melanie Bien, of Savills Private Finance, the mortgage broker, said: “Anyone who has remortgaged in the past few years – and that is a lot of people – will be able to make a claim, depending on their lender’s stance. Lenders are concerned about the scale of claims they are likely to see regarding exit fees, which may be why borrowers will have to make a claim themselves, rather than wait to be contacted by their former lender.”

Some mortgage lenders have more than doubled their exit fees since 2003 and the highest charge is £295. Customers who were forced to pay higher fees than they had agreed to when taking out their mortgage deal are eligible for a refund.

For example, a borrower who signed up for a three-year mortgage deal with Abbey in 2003 will have agreed to pay an exit fee of £99. But when they redeemed the mortgage last year, they would have been charged £225, as the lender increased its fee in May 2005. This customer could reclaim £126 from Abbey.

Kensington, a sub-prime lender, was last night the only home loan provider to refuse to refund inflated exit fees. Northern Rock, the fifth-biggest lender, said this year that it had set aside £15 million to cover the cost of refunding mortgage customers. But Halifax, which published its annual results yesterday, made no provision for the cost of refunding customers, despite having the largest share of the market.

The watchdog’s demands came as a blow to banks, which are being deluged with demands from customers seeking refunds for “illegal” overdraft charges, some of which are as high as £39.

Some experts said that this could cost the banking industry billions of pounds. The Office of Fair Trading is investigating the charges and is expected to announce its findings later this month. Last year the OFT ordered banks to reduce penalty charges on credit cards.

Most lenders refused to budge on their exit fees after the FSA announced its investigation. Only two lenders said that they were cutting their charges. Portman Building Society cut its fee from £199 to £145 last month, while Skipton Building Society will cut its fee from £175 to £125 from April 1. Other lenders said that their fees were under review.

Ray Boulger, of John Charcol, said: “The big plus from the FSA report is that it has made things a lot more transparent.”

The fightback gathers strength

Cost of the customer campaigns

– Exit fees are the latest in a sustained consumer backlash against financial institutions
– Last year the OFT capped credit card penalty charges at £12, limiting a lucrative source of income for the issuing companies – Customers have also been displaying their displeasure at bank charges for going into the red without permission
– Consumer bodies have encouraged them to reclaim these charges and banks have been paying up before the cases reach court or the Financial Ombudsman
– More than a million template letters to help people to reclaim overdraft charges have been downloaded from one consumer website. The OFT will rule on overdraft charges this month