Police are urging Wilmslow shoppers to think before they punch their pin number into a chip and pin device.
Over the past few months there have been four distraction thefts at supermarkets in East Cheshire, including one at a Wilmslow store.
DS Andy McGillan said: "Shoppers are unwittingly giving their pin numbers away by not being vigilant as to who is watching over their shoulder while they pay at the till.
"Then when they load their car leaving their handbag unattended, a stranger engages them in conversation to distract them.
"Meanwhile another person is rooting through the handbag to steal credit and debit cards.
"Before the victim even realises their cards are missing, the thieves are siphoning as much money as they can out of the victim's account. If the bank thinks the pin number hasn't been protected adequately, the victim may have to rely on their bank's goodwill to get their money back."
Shoppers are urged to check no one is watching when they punch their pin into the chip and pin device and always attempt to conceal the number.
DS McGillan added: "Also be aware in the car park. Ensure your bag is secure and keep it with you at all times. Don't leave it on the car seat or in the trolley while you load your shopping into the boot."
The offenders, who are thought to be eastern European, are believed to be working in groups. In the past few months they have also targeted Crewe and Nantwich.
DS McGillan said: "Anyone who sees someone acting suspiciously in a supermarket and its car park should contact police on 0845 458 0000.
"While we make every effort to hunt down the offenders and bring them to justice, we would urge people to be vigilant."
