Fraudsters have installed card traps at a number of ATMs across Belfast, police have warned.
The PSNI issued a warning to the public following the discovery of four so-called 'card traps' at cash machines in recent days.
Card traps are attached to a cash machine by criminals to enable them to trap a bank card.
The victim is then unable to recover the card from the machine leaving criminals able to recover it later. The device is fitted into the card slot on the ATM and the only thing visible from the outside is the edge of a thin piece of black plastic.
Police have not disclosed the number of victims caught up in the recent scam.
In May, alleged members of a UK/Republic of Ireland-based organised travelling crime gang were arrested in relation to a series of ATM frauds.
The gang members are accused of having targeted cash machines with sophisticated skimming devices across Northern Ireland including east Belfast, Portadown, Enniskillen, Rostrevor, Magherafelt and Newry.
The skimming devices the PSNI uncovered at the time had similarities to one which was used in the north of England.
Last month a skimming device was found on a cash machine in Lisburn.
Detective Constable Stephen Crooks, from the PSNI Economic Crime Unit, said: "Card traps are devices designed to trap cards as they are inserted in the ATM. A miniature camera may be hidden, overlooking the PIN pad to capture the PIN being entered, or a suspect will be 'shoulder surfing' behind their intended victim.
"They will then wait until the intended victim leaves the area and will retrieve the debit or credit card from the ATM."
Mr Crooks added if anyone suspects a card trap is fitted to an ATM, or locates one close by, they should report it to police.
"Do not handle it or try and remove it from the ATM, as it has sharp edges and may cause injury," he said.
Police also advised cash machine users to cancel the transaction and use a different machine if someone makes you feel uncomfortable. Also, never allow yourself to be distracted, always shield the keypad, put your money and card away before leaving the machine and if the cash machine does not return your card report its loss immediately to the card company.
Business owners who have ATMs at their premises have been advised to inspect them regularly for anything suspicious fitted to them.