Virus Shield promised to protect smartphones from harmful apps and to scan files, settings and media in real time for ultimate peace of mind, and all for just $3.99.

Simply download it, launch the app and a graphic on the screen would reassure users that everything was OK. If they could see a graphic of a shield with a tick through it, rather than a cross, then there was nothing to worry about.

Within a week of launching, the app had been downloaded more than 10,000 times and had an average review score of 4.7. However, there is just one catch, as Michael Crider from Android Police discovered: it's all a big con.

"It's a complete and total scam. We don't mean in the slightly skeevy way that some anti-virus and general security software overstates dangers and its own necessity. We mean it's literally a fake security app: the only thing that it does is change from an 'X' image to a 'check' image after a single tap. That's it. That's all there is, there isn't any more," he wrote.

Google does have safeguards in place when it comes to potentially malicious apps. All submissions to the Google Play store are scanned for malware or suspicious code. But of course Virus Shield doesn't contain a virus and so was accepted.

This open approach, which is one of Android's best features, can also be its biggest flaw. Google's more ‘relaxed' approach to app validation has led many consumers to take extra precautions in protecting their devices, and one of those precautions has been to invest in an anti-virus app because of the bigger threat of malware.

The good news is that following Android Police's report, the app has now been pulled from Google Play. The bad news is that thanks to its good reviews and the fact that it was near the top of the paid-for apps charts, thousands of smartphone owners have already spent money on something that potentially exposed them to a greater virus and malware risk.