The Irish Payment Services Organisation (Ipso) says con men purporting to be point of sale terminal engineers have tricked a number of retailers into allowing them access to the terminals and PIN pads in their stores.

Reports say around 9000 credit and debit cards have been skimmed in the scam. It has also been reported that, towards the ends of last week and over the weekend, police seized 47 doctored Chip and PIN devices from targeted stores.

It is thought that around five shops in the north east of Ireland were targeted on Friday by the gang, who claimed they were doing maintenance work on eftpos terminals on behalf of banks.

While in the store, existing terminals were replaced with compromised units which had been programmed to copy data from the mag stripe on cards and harvest PINs. This information is used to create cloned cards that can be used to make fraudulent transactions in countries that have not introduced the Chip and PIN system.

Ipso says it is working with police, banks, card issuers, terminal manufacturers and other relevant bodies to examine the details of the fraud so that action can be taken to minimise its impact.

Úna Dillon, head of card services, Ipso, says any cardholders that suffer a loss due to the fraud will be reimbursed by their bank or card company.

In a separate incident earlier this month, Ipso said hundreds of Irish bank cards were cancelled after fraud monitoring systems detected suspicious transactions paid to a US-based e-commerce merchant.

Ipso said monitoring systems began picking up unusual activity on consumer card accounts, with small payments of between EUR1 and EUR2 made to a US site. These low value transactions alerted monitors to possible 'test sales', which are used by criminals to confirm that stolen card details are still valid.