Hundreds of Irish bank account holders have had their cards cancelled after fraud monitoring systems detected suspicious transactions paid to a US-based e-commerce merchant.
The Irish Payment Service Organisation (IPSO) says monitoring systems began picking up unusual activity on consumer card accounts a couple of days ago, with small payments of between EUR1 and EUR2 made to the US site.
The IPSO says these low value transactions alerted monitors to possible 'test sales', which are used by criminals to confirm that stolen card details are still valid.
Fraudsters usually then use the validated card numbers to purchase high value goods which can be sold on quickly for cash. But in this case fraud monitoring systems picked up the activity and the cards were blocked, meaning a "major fraud problem" was avoided, says the IPSO.
The stolen card details are thought to have come from a retailer's database. The IPSO says it is investigating the matter and has not yet established how criminals obtained the data, although it could have been collected by a member of staff or hacked.
Banks are contacting affected customers and reissuing cards, although some people may have been declined at the point of sale yesterday, says IPSO.
The theft comes to light days after US authorities indicted an international criminal gang thought to be responsible for the theft and sale of over 40 million credit and debit card numbers that were hacked from the computer systems of nine major US retailers.