ATM machines in Blackwood, Risca and Ystrad Mynach have been targeted by criminals looking to clone cards.
Card skimmers have been found on machines on Barclays Bank Cashpoint machines and residents are being warned by Gwent Police to be vigilant.
After a person has inserted their card, is is retained and the screen displays a notice that the ATM is out of order.
The card is then retrieved by the criminals and will be used a short time later.
Report any suspicious behaviour when using the ATM’s by telephoning 01633 838111.