Police are urging shop workers in Northumberland to be extra cautious after two men conned a Post Office cashier out of cash in Alnwick.
At 11.43am on Saturday, two men went into the Post Office on Wagonway Road. They had £660 in £10 notes and asked to change it into £20 notes, which the staff member did.
They then said they wanted euros instead, but the cashier refused, realising that it could be a scam. She gave them the £10 notes back, in return for the £20 notes, but they had cunningly removed some of the £20 notes from the bundle.
Police have descriptions of the two men, both of Eastern European appearance.
One is described as being in his early 30s, 5ft 5inches tall, medium build, short dark hair and beard. He was wearing a dark-coloured baseball cap, light-coloured shirt and jeans.
The second is described as being in his early 20s, 5ft 3inches tall, fat build, longer black and curly hair and was wearing a white T-shirt and khaki-coloured pants.
Officers are keen to hear from anyone who may have been in the Post Office at the time or has been a victim of a similar con, known as ringing the changes.
Anyone with information should call police on 101, quoting reference number 056114A/16, or ring the independent charity Crimestoppers on 0800 555111.