Facebook is pulling a scheme that mined highly personal data from paid volunteers, after it was exposed.
TechCrunch said participants – including those aged 13-17 – had been paid up to $20 (£15.30) a month to open up their phones to deep analysis, according to the BBC.
The news site said the iOS app involved appeared to breach Apple's privacy protection policies.
TechCrunch reported that Facebook used social media ads to target teenagers for the plan. Facebook denies this.
A spokeswoman for the social network was unable to say whether it ran the program in the UK or other countries outside the US.
The app had the potential to provide Facebook with "nearly limitless access" to a user's device including:
- the contents of private messages in chat apps including photos and videos
- web browsing activity
- logs of what apps were installed, and when they were used
- a location history of where the owner had physically been
- data usage
In addition, TechCrunch reported that users were asked to provide screenshots of their Amazon orders.
When the BBC visited one of the sign-up pages, it stated that Facebook would use the information to improve its services.
It added that "there are some instances when we will collect this information even where the app uses encryption, or from within secure browser sessions.”