Bank of Ireland has confirmed that several thousands of its customers have been affected by a scam in which cardholders' details were stolen.
The bank said it will issue affected customers with new cards, after a criminal gang skimmed cards in a small number of retail outlets.
The Garda Bureau of Fraud Investigation has seized 47 bogus chip and pin devices, that copied the credit and debit card details of thousands of people at the weekend.
The devices, were placed in machines, and contained a memory chip and a sim card, allowing the criminals to gain access to the card details and pin numbers of a customer's card.
The details were then transmitted to a centralised system, for the criminals' own purposes.
Gardaí are warning retailers to check their devices.
If a suspect device has been placed inside the machine it may be 30 to 50 grams heavier.
Gardaí fear there could be more of the bogus devices in retail stores around the country.
The individuals involved fitted devices to sales terminals while pretending to carry out maintenance work on behalf of banks.
This enabled them to gather the details of cards that have been used at the shops.
The Irish Payment Services Organisation says any losses by customers will be reimbursed.
The scam, which was uncovered over the weekend, involved a small number of retail outlets, according to the IPSO.
It says an investigation is ongoing but says consumers should not be too concerned as anyone who has been affected by the fraud will be refunded by their bank.
Retailers are being advised to check the identity of anyone claiming to be carrying out work on behalf of their bank.
Those travelling abroad in the next week are advised to make sure restrictions have not been put on their bank cards.
