Children are duping their parents with a mobile phone app which lets them store videos and pictures in secret.

Private Photos (Calculator %) is rated suitable for anyone over the age of four, and is available on iTunes for free.

It looks just like a harmless calculator when you open the app, but when you punch in a unique, four digit code, they can unlock scores of private photos and videos.

While it is billed as a 'child friendly' app, the image is of a photo showing a woman's cleavage.

For just £1.99, they can upgrade to the full version which will automatically pap 'intruders' who try to gain access through the app without having the proper passcode.

You can also use the app to write and store private notes and securely surf the internet with a private browser.

Other apps with similar settings include Secret Calculator Vault and Calculator + Photo Lock Vault.

A spokesman told the Mail on Sunday : "The Calculator app is essentially a secret photo album that children can use to hide photos or videos from their parents.

"The photos are hidden from view behind an icon that looks like a calculator.

"We would urge parents to be vigilant and discourage their children from using such an app."