A study of more than 30 popular Android phone apps by campaign group Privacy International found at least two-thirds sent personal data to Facebook from the moment they were opened – before users could be asked for consent and regardless of whether the subjects were Facebook users.

Privacy International identified Skyscanner, TripAdvisor and Kayak as among the apps which sent personal data to Facebook without users’ consent.

The researchers examined apps with built-in Facebook trackers and intercepted data as it was sent.