Northern Rock and Bradford & Bingley, the government-backed lenders, could be forced to scrap charges levied on struggling homeowners who slip behind with mortgage payments, after accusations that the fees are unfair.

Northern Rock, which is wholly owned by taxpayers, collects more than £1 million a month in arrears charges.

The controversy echoes the one about overdraft charges, which will come to a head today when the Court of Appeal rules on whether the Office of Fair Trading (OFT) should be allowed to investigate their fairness. The ruling comes after a two-year fight between the OFT and six banks and Nationwide Building Society. They are appealing against a High Court ruling that backed the OFT.

Charges on mortgage arrears, which can reach £55 a month, are not part of the current court case, but have become an increasingly contentious issue as the economic crisis has intensified.

Northern Rock imposes a £55-a-month fee on mortgage customers who are three months in arrears, or £25 a month if only two payments have been missed. Bradford & Bingley (B&B), whose mortgage book was nationalised in September, levies a £25-a-month penalty from the moment that a borrower falls one month in arrears.

Both lenders have told The Times that the charges are under review after criticism from debt charities, which argue that the fees make a bad situation worse for overburdened households. B&B said that it was likely to “improve” its penalty structure in the interests of customers and promised to release further details next week.

Chris Tapp, of CreditAction, a debt charity, said: “These charges from lenders owned by the taxpayer have the effect of pouring salt into the wound, compounding the problem for families unable to make their mortgage payments. The logic seems warped.” Debt charities have drawn parallels between mortgage arrears charges and the penalties that banks levy on customers for going overdrawn.

Cathy Neal, of Which?, the consumer association, said: “There are certainly comparisons to be made between current account charges and arrears charges. We would hope that these charges closely reflect the cost to lenders of a mortgage in default. Lenders are under pressure to be seen to be operating in a fair way in the area of arrears and repossessions, particularly those that are government-owned.”

Almost every high street bank, including Halifax, Abbey and Lloyds TSB, along with specialist lenders such as GMAC, charges between £10 and £55 a month for each missed mortgage repayment. Lenders say that the charges cover administration costs in dealing with borrowers in default. They also say that charges are likely to be waived if a customers makes an arrangement to clear the arrears.

Halifax, which charges £35 for every letter sent warning that a customer is in arrears after an initial request for payment, said that the charges “bore a close relationship with the costs to the bank”, but admitted that they were also “based on conditions in the market”.

Woolwich, part of Barclays, said that its £27.50 monthly arrears charge was under review.

Ray Boulger, senior technical manager at John Charcol, the broker, said: “A monthly fee is a serious impediment for a homeowner to get back on track.

"If lenders charge a flat rate regardless of the circumstances then is would be hard to argue that it is fair and could even contravene FSA rules on treating customers fairly.”

The Financial Services Authority is reviewing mortgage arrears charges and is expected to report in May.

Northern Rock said: “Our approach to helping customers who are experiencing payment difficulties is very much based on individual assessment of circumstances. It involves working with customers over prolonged periods using specially trained staff.”

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