German security firm Protecus has found a setting in the fifth beta release of Apple's iOS 7 software called Feature Locations that tracks a user's GPS coordinates over time and plots them on a map.
This news comes after code was discovered in Google's Android 4.3 software that lets devices scan for nearby networks, in order to determine a person's location, even when Wi-Fi is turned off.
The Apple feature is relatively hidden away on the iOS 7 software - due to be released in October - in Settings, Privacy, Location Services, System Services and Frequent Locations.
It is unclear whether the feature is turned on by default but according to the Protecus security expert: '[The feature] kept track of my complete movement profile (location and time tracking) without me knowing anything.'