A 62-year-old partially sighted man lost £300 to thieves who used a distraction technique to steal his bank card.
The man was targeted while he was using his card at a cash machine inside a bank in Belgrave Road, Leicester, last week.
Police believe a man who began chatting to the victim as he used the bank machine did so in order to watch him enter his four-digit number.
As the machine was about to dispense money, he then distracted the older man's attention, while an accomplice rushed in to grab both the cash and bank card. The thieves were then able to use the card to withdraw £300 from the man's account at another bank machine in the same area.
The victim, who has asked to remain anonymous, said: "I was withdrawing my money and my attention was distracted by a man who spoke to me.
"While we were speaking, someone else stole my card.
"I was very upset to lose my money."
Police are treating the theft, which happened at 1.40pm last Thursday, as an isolated incident.
Previously, however, the force has seen clusters of similar thefts.
Inspector Ed McBryde-Wilding, commander of Keyham Lane police station, said there was concern the men would strike again.
He said: "It's an offence which occurs periodically, but this incident is not part of a trend.
"We are telling the public about this incident because we don't want it to become a trend."
Pc Donna Hyde, of the Belgrave Safer Neighbourhood Team, said: "This was a despicable crime in which a vulnerable, elderly man has been targeted by thieves.
"He didn't stand a chance really.
"Once they had distracted and confused him they were able to steal his card, and then withdrew his money from another bank."
Police have issued this advice when using bank machines includes:
Beware of strangers who talk to you or stand very close while you are using a cash machine.
If in doubt, withdraw your card and leave.
If you are a vulnerable person, have a friend or relative with you when you use a bank machine.
Keep your handbag or purse in a secure, zipped-up bag.
Although this offence was committed inside a bank premises, it is safer to use an ATM inside a bank than a machine in a public area.
Anyone with information about the incident should contact Pc Hyde by calling her on 101, or Crimestoppers, which is anonymous, on 0800 555 111.
