A skimming device was discovered fitted to the card slot on a pump at a local filling station in Cookstown yesterday.
Police are warning the Mid Ulster public to be on the lookout for anyone acting suspiciously around filling station forecourts.
A PSNI spokesman said: "This was a very well disguised device and full credit goes to the alert individual who spotted it. Enquires are continuing as to its origins and when it was put there.
"If you notice anything attached to an ATM machine or fuel pump machine which looks out of place, do not touch it, stop the transaction immediately and alert police as well as the bank.
Skimming devices can be attached to machines by criminals to enable them to copy information from your bank card so they can remove money from your account."
Police advise customers to follow the advice below to ensure safe transactions;
• Make sure you hide your pin number while at an ATM as criminals may be watching;
• Be aware of your surroundings. If you are talking on a phone or wearing headphones you can't take in what is going on around you;
• Cardholders should also guard their personal identification number (PIN) more carefully and be aware that any form of distraction or assistance while they are using an ATM could mean someone is trying to steal their dispensed money or their card.
• If someone tries to distract you and you feel unsure - cancel the ATM transaction.
• Do not be complacent - a robbery can occur in crowded environments, not just deserted streets.
Anyone who would like further advice or has information in relation to skimming devices should contact their local police on the non-emergency number 101.