The Central Bank has said one in five payment protection insurance policies it has reviewed so far were in breach of the bank's consumer protection code.

The bank today gave an update of its on-going investigation into the sales of payment protection insurance (PPI) policies.

It said said that so far about €25m has been identified for refund to those customers whose files have been reviewed.

Eleven financial institutions are being investigated, including AIB, Bank of Ireland, Bank of Scotland, Danske Bank, EBS, GE Money, KBC Bank Ireland, MBNA, Permanent TSB, RaboDirect Bank Ireland and Ulster Bank.

About 350,000 PPI polices sold since July 2007 are included in the review and so far, over half of these have been reviewed by the financial institutions. Of these one in five breached the bank's code.

The Central Bank said it will continue to monitor the lenders to ensure that their reviews have been completed by the end of 2013 and to its ''satisfaction''.

''Following our initial investigation, we have required firms to undertake a review of PPI sales since July 2007, overseen by independent third parties, to write to all affected customers, and to offer a refund or retention of their PPI policy,'' the bank's Director of Consumer Protection Bernard Sheridan said.

He said that all consumers with policies that fall within the scope of the review will be contacted by their financial institution by the end of the year.

''Consumers who are not happy with the outcome of the firm's review or who are unhappy with any element of the sale of their PPI policy should contact their firm directly,'' the bank added.