Police in Edinburgh are appealing for information and urging businesses to be vigilant following a number of frauds and attempted frauds via card devices.
Whilst others distract staff, the customer in control of the terminal manipulates the machine into fraudulently refunding them significant sums of money.
At least eight incidents have taken place since Saturday 4th May in the city centre, Haymarket and Blackhall areas and have resulted in a minimum of £32,000 being stolen.
All are being treated as linked and the two male suspects are both described as black, aged 20 - 30 years old, of slim build, around 5ft 8ins tall, with English accents.
On one occasion they were in the company of two other men and, on another occasion, were with a woman described as being mixed-race with a London accent.
Detective Inspector Gordon Burns of the East's Economic Crime Unit said: "These fraudsters tend to target small businesses, as they typically have less staff than major retailers.
"One person takes control of the card machine, and another tries to distract staff while their accomplice manipulates this and refunds a substantial amount of money onto their card.
"Distraction techniques are not a new phenomenon. However, with more sophisticated payment technology available the use of card devices within these seems to be an increasing trend.
"I’d urge staff to treat the terminal like the till - always ensure you are in control of the transaction and have sight of the device.
"Be wary if someone is taking longer than five to ten seconds to type in their PIN, of if someone is else is trying to get your attention during this time.
"Businesses can install additional security measures on these devices to prevent refunds being given without specific authorisation, and should speak to their acquirer for further advice.
"If you think you may have been a victim of this contact your bank immediately, secure any CCTV and contact Police Scotland via 101."
Anyone with information about these incidents who has not already contacted Police Scotland should call 101, quoting reference 2723 of 20th May, or report information anonymously to Crimestoppers on 0800 555 111.