The Angry Birds, Pandora and TextPlus 4 iPhone apps have all been accused of sharing data with third parties without user consent.

Investigations conducted by the Wall Street Journal found that 56 of 101 apps it tested on the iPhone and Google's Android OS passed on private information to advertisers.

Data such as a handset's UDID (unique device identifier), location and the owner's age and gender was routinely shared with advertisers with TextPlus 4, a text-messaging app, found to be sending data to eight separate advertisers.

Paper Toss, a game available on both the iPhone and Android platforms, was found to share data with five different advertisers.

Apple insisted that privacy and trust were vitally important to the company, saying that it it had created "strong privacy protections" for data-sharing, particularly with location-based information.

The study also found that 45 of the apps didn't provide a privacy policy within the app or on the publisher's website. Apple does not require apps in the App Store to provide a privacy policy.