Supermarket shoppers are being warned to steer clear of Tesco and Waitrose coupons being shared on Facebook.
The fake vouchers - for £100 and £75 respectively - are claimed to be up for grabs to celebrate the two supermarkets' anniversaries.
However, not only are the anniversaries fake, the coupons are too. To get hold of one, people are asked to click on a link to visit a website.
"If you click on the convincing looking URL you will be taken to a fake website designed to trick you into handing over personal information," says Action Fraud.
"According to security researchers, once you click on the malicious link fraudsters also collect personal information from your device by installing cookies on your phone that track you, or add browser extensions that can be used to show you advertisements."
Anybody that has fallen for the scam and clicked on the link should run a virus scan.
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There are several giveaways that the Waitrose voucher is fake. It refers to 'this coupons', for example, and says it 'cannt' be used with other coupons.
The Tesco coupon, though, is rather more convincing - although a spokesperson points out that it isn't being shared through official channels.
"I can confirm that this is not a legitimate Tesco promotion. Any Tesco offers run through Social Media will be run through an official Tesco Facebook/Twitter page," she says.
You can tell if it's an official page as there will be a blue tick next to the name. I would not advise for you to either click on the link or to enter in any requested details."
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Both Tesco and Waitrose say they've asked Facebook to take the coupons down.
Fake coupons are a widespread problem on the internet. Recently, an Aldi version was found doing the rounds, purporting to offer £65 off a supermarket shop.
And late last year, fake vouchers for Topshop, Marks & Spencers, Iceland and Sainsbury's were widely shared.
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To protect yourself, simply installing good anti-virus software and keeping it up to date should do the trick; but to be on the safe side, you should never click on a link unless you're absolutely certain it's what it claims to be.
And use your common sense: if an offer appears to good to be true, then it probably is.