Some of the most popular Android apps are exposing user information like contacts, calendar and location, a new study has found.
Research by MWR InfoSecurity found that when some apps are downloaded, information is not just shared with the app manufacturer. One researcher said: 'We found that a lot of the free applications in the top 50 apps list are using advertising inside the applications, and that the permission that you grant to these applications is also granted to the advertiser.
'If users knew about this, I think they would be concerned about it. But at the moment I don't think they are aware of the situation and how widely their information can be used.'
The researchers found code in some apps from US ad agency MobClix, which gives advertisers access to personal information. Google said it has best practice advice for app manufacturers but it does not screen applications before they are available on marketplace.
Viviane Reding, vice president of the European Commission, told Channel Four News: 'This really concerns me, and this is against the law because nobody has the right to get your personal data without you agreeing to this.
'Maybe you want somebody to get this data and agree and it's fine. You're an adult and you can do whatever you want. But normally you have no idea what others are doing with your data.
'They are spotting you, they are following you, they are getting information about your friends, about your whereabouts, about your preferences.
'That is certainly not what you thought you bought into when you downloaded a free-of-charge app. That's exactly what we have to change.'
Editor: Graeme Neill