Security firm Symantec is warning of new malware masquerading as two apps on Google Play that claimed up to 100,000 victims before the malware was removed.
The Trojan would secretly send text messages from the victim's device to a premium rate number, resulting in a high phone bill.
After sending texts to the premium rate number the app would uninstall itself.
A researcher at Symantec said: "What is most interesting about this Trojan is the fact that the threat managed to stay on Google Play for such a long time,"
The Trojan called "Android.Dropdialer" was discovered in two applications.
Both "Super Mario Bros" and "GTA 3 Moscow City" racked up 50,000 to 100,000 downloads after being posted on Google Play.
If you are concerned that you have a Trojan on your Android mobile or tablet you can install a free application from Sophos Mobile Security that automatically scans apps as you install them. It also has a feature that can scan previously installed versions too.
To report a fraud, call Action Fraud on 0300 123 2040 or use our online fraud reporting tool.