A malicious new app known as Adult Player has been secretly photographing it's users and blackmailing them into paying for the images.

Luring customers on to the app with XXX-images and videos, the app then takes a snap of the phone users, and promptly locks down the device.

A message is then sent to the phone users, threatening to leak the images and keep the phone locked unless they pay $500 through a PayPal account. This form of hacking is known as 'ransomware', with experts stating that even if users do pay the amount, the hackers will most likely still leak the photographs and keep the phone locked.

While the Adult Player app isn't available through normal app stores such as Google Play or Apple's App Store, the app can be downloaded directly from an internet browser.

Tech advisers inform customers that if they have downloaded the app, the best course of action is the put your phone into safe-mode, which will only allow all pre-installed apps to work on the device, and will allow users to delete the app safely.