Bank "costumers" are warned their debit cards could combust in a fake letter circulating on social media.
A copy of the letter, purporting to be from 'Barclays' and warning of a fault at its "Molton Keynes" factory, was shared by Cheshire Police.
The letter said the cards may cause a "pocket fire" and asks people to send in their cards along with pin numbers.
Barclays said a number of customers had reported getting the letter "which should be ignored".
Calling it the "worst scam ever", police said warnings over giving out bank details were unnecessary in this instance.
The letter, sent as a "precushion", prompted more than 1,000 replies after it was put on social media.
This letter from 'Mr Smith' at 'Barclays' is warning people about Spontaneous Debit Card Combustion...🕵️♂️— Cheshire Police (@cheshirepolice) June 27, 2019
We would usually tell people to #TakeFive before giving out their bank details.. I don't think we need to for this one 😂 https://t.co/ANZISkBIdN#WorstScamEver pic.twitter.com/6FEaWHfx5Y
One Facebook user said: "I think their pants may be on fire."
Another added: "All around the country post boxes, post offices and mail sorting offices are burning down. They didn't think this through."
While on Twitter, a commenter said: "You just hope that everyone sees it for what it is."
A Barclays spokesperson said: "A number of customers have reported receiving letters pertaining to be from 'Barclays Bank Debit Card Factory' in 'Molton Keynes'.
"These letters are a scam and customers should ignore the instructions given.
"Your bank will never ask for your card to be returned, PIN number or account details."
Cheshire Police said it had not had any reports of anyone receiving the letter but its Financial Abuse and Safeguarding Prevention Officer had been made aware of it and wanted to use it as a chance to promote the Take Five fraud prevention campaign.
Blogger Simon Harris, from Essex, has since come forward to claim he created the letter in 2018, as a joke and show that "there are people on the internet who will literally believe anything".
"So many people have been commenting on it, saying how bad it is... it just proves my original point," he said.
"But, if it stops one person losing out to scammers, it will have been worthwhile."
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