The Guardia Civil has issued a warning about a scam targeting people whose bank cards become trapped inside cash machines.

Police said customers should be immediately suspicious if a stranger appears and offers assistance shortly after an ATM fails to return their card.

‘The person who appears to ‘help’ you suspiciously quickly may already have been waiting,’ the force warned.

Criminals can tamper with a cash machine’s card slot so that the card appears to have been swallowed.

An accomplice may then approach the victim, posing as a helpful passer-by.

The fraudster may attempt to watch the victim enter their PIN, persuade them to type it again or ask them to reveal it directly.

Once the customer leaves, the criminals can retrieve the trapped card and use the stolen code to withdraw cash or make purchases.

What to do if an ATM keeps your card

The Guardia Civil advises customers never to disclose their PIN to anyone, regardless of how helpful or convincing they appear.

Users should contact their bank directly and only call an official telephone number obtained from the bank’s website, mobile app or the ATM itself.

Customers should not rely on a telephone number provided by a stranger or displayed on a suspicious sticker attached to the machine.

If anything unusual is visible around the card slot and it is safe to remain at the location, the customer should avoid leaving until they have contacted their bank and blocked the card.

Anyone who believes an ATM has been tampered with should also alert the police.

The Guardia Civil added: ‘If the cash machine does not return your card and someone appears willing to help, that is precisely when you should be suspicious.’