Allied Irish Bank has confirmed it is writing to approximately 11,500 customers in relation to discrepancies attached to insurance options on credit cards.
The bank said it would be refunding the affected customers in the coming days.
The refund amount totals €3.1 million euro.
AIB said the discrepancies were found during a review of all credit card accounts and relate to insurance options.
The products involved include the Payment Protection Plan, Travel Insurance and Card Protection.
The bank says that the Central Bank has been notified.
The bank says that the review programme was undertaken in line with agreed processes relating to customer refunds. In any case where doubt existed, the bank said, the benefit of doubt was given to the customer.
The bank says the fault lies in the bank's internal verification systems, and that changes are being implemented to prevent any reoccurrence.
The letter being issued to customers in the coming days will include contact details for a dedicated helpline at AIB's contact centre.
