Attempts to steal people's bank cards and Pin codes while they are using cash machines have tripled over the past year, according to figures.
Financial Fraud Action UK says there were 7,525 incidents in the first four months of the year, compared with 2,553 in the similar period in 2012.
It said the numbers appeared to be increasing every month.
Police say the rise is partly because more secure chip-and-pin cards have cut the scope for hi-tech fraud.
The data was gathered by Vocalink, the company that operates the UK's national payments infrastructure, and publicised by Financial Fraud Action UK, an industry body responsible for co-ordinating the prevention of card and payments fraud.
In a practice the police call shoulder surfing, thieves look over a person's shoulder while they key in their number at cash machines and then distract them as the card comes out of the ATM, enabling the thief to snatch it.
There were just over a billion ATM transactions in the UK during the first four months of the year, according to data from the UK cash machine network Link.
Eighty-year-old Jacqueline Fletcher from Bletchley told BBC News she was watched by two thieves while she withdrew cash from an ATM outside her local supermarket.
When she emerged from the shop later, one of the pair asked her for change and stole her bank card while pretending to help her with her purse.
"It frightened me," she said, "and it gutted me to think that I'd been stupid enough and that they'd been attacking vulnerable people, young or old.
"It's obvious that they'd seen me as an easy mark."
The perpetrators used the card to lay £400 in bets at Ladbrokes and withdrew £240 in cash.
'Tried and tested'
The head of the dedicated cheque and plastic crime unit, Det Ch Insp Dave Carter, puts part of the blame on the introduction of more secure chip-and-pin cards and better designed cash machines.
The innovations make it harder for criminal gangs to use sophisticated equipment to copy the details on cards.
"This equipment is difficult to get hold of, it's obviously illegal to possess it. It tends to be quite hi-tech and therefore it's expensive, " he explained.
But tricking bank customers out of their cards, depends on the tried-and-tested techniques of petty crime, he said.
"This is a complete return to a simple distraction or con tactic if you like, so it's a lot cheaper and it can be effective."
A common distraction tactic is to engage the victim in conversation just as the card is being ejected.
Jacqueline Fletcher's bank, Barclays, returned the £640 she had lost, but some banks can be reluctant to pay refunds if people have been careless with their Pin codes.
Police say the obvious way to frustrate thieves is to shield the Pin code pad while you are entering the number, with an object or your spare hand.
Card providers are concerned that significant numbers of customers still do not bother to take this precaution.