Building society Nationwide today warned its contribution to a compensation pot for savers in failed banks could hit £250 million.

All UK banks and building societies pay a levy to the Financial Services Compensation Scheme, which compensated savers who lost money through the collapse of the Icelandic banks and Bradford & Bingley.

However, Nationwide said the levy paid to the scheme was unfair on building societies as it did not reflect the fact that banks took on a much greater level of risk.

It has lobbied the Treasury, Financial Services Authority and Bank of England about the charge, which it said penalised its membership.

A spokesman said: "We feel as though our members have had to bear a significant element of the cost of the failed banks, even though banks take on substantially greater levels of risk than we have ever been prepared to."

He added that as a mutual organisation the cost would ultimately be borne by Nationwide's members, although he did not expect it to have a direct impact on the product rates the group offered.

The group said it was still considering the most appropriate way to recognise the estimated £250 million charge, which covers a three-year period and could change in line with interest rate movements, in its accounts.

It currently expects to include a charge for the full amount in its 2008/2009 financial statement.

However, £13 million of the total which relates to the former Derbyshire and Cheshire Building Societies, which have been taken over by Nationwide, will be included in the accounts relating to their acquisition.

The Building Societies Association has been campaigning about the "disproportionately high" share of the FSCS bill which is being borne by the mutual sector.

It argues that the charge, which is based on the level of retail deposits held by individual institutions, is unfair because building societies take less risk and are better capitalised than banks, and are therefore less likely to fail and call on the scheme.

Skipton Building Society recently blamed its share of the compensation bill as a major factor contributing to an 86% dive in profits.