Fraudsters are conning older people out of thousands of pounds by asking them to pay off a non-existent tax debt in iTunes vouchers.
The tax people HMRC says hundreds of people have fallen victim to a scam in which a fraudster makes a call and tells them they owe a significant amount in tax, and says it can be paid off by buying iTunes gift cards.
Action Fraud said there has been 1,500 victims, mostly over the age of 65, with an average financial loss of £1,150 though some have lost much more.
It comes after an 81-year old Hertfordshire man lost £20,000 in the scam.
The victim from Rickmansworth was repeatedly targeted by fraudsters, receiving thirteen calls from men claiming to work for Her Majesty's Revenue and Customs.
On each occasion they stated that the victim had an outstanding debt that needed to be paid, before telling him to purchase thousands of pounds worth of iTunes vouchers. The fraudsters later called back and asked for the codes on them.
A member of the public became suspicious after seeing the man purchase a large quantity and police were contacted.
In all, the victim purchased 267 vouchers.
Angela MacDonald, HMRC's director general of customer service, said: "It's really reassuring to see reports of supermarket staff, off their own back, taking action to keep customers safe.
Raising public awareness is the best safeguard against this vicious scam. Supermarket staff are often the last line of defence against these fraudsters.
That's why I've written to the chief executives of major UK retailers to urge them to make their staff aware of this scam so they can help protect unsuspecting customers".
Detective Constable Nick Surridge, from the Three Rivers Local Crime Unit, added: "Unfortunately these fraudsters can be highly convincing and often prey on the trusting nature of their elderly victims. I would urge people to please remain vigilant if they receive calls of a similar nature. Legitimate organisations would never request payments to be made in iTunes, or any other kind of voucher.
If you aren't sure, end the call and contact police on 101. Remember to wait at least five minutes, or use a different number, to ensure you are not reconnected to the offender.
We want to get this message out as widely as possible to prevent others falling victim to this cruel scam. I would ask that people please share this information with older friends, relatives and neighbours, who may not otherwise have heard about it".
:: If you have been called in similar circumstances, please contact police on the non-emergency number 101.