Facebook asked to curb data gathering activities in Germany.

BONN: Facebook has been ordered to curb its data collection practices in Germany after a landmark ruling on Thursday that the world's largest social network abused its market dominance to gather information about users without their consent.

Germany, where privacy concerns run deep, is in the forefront of a global backlash against Facebook, fuelled by last year's Cambridge Analytica scandal in which tens of millions of Facebook profiles were harvested without their users' consent.

The cartel office objected in particular to how Facebook pools data on people from third-party apps - including its own WhatsApp and Instagram - and its online tracking of people who aren't even members through Facebook 'like' or 'share' buttons.

'In future, Facebook will no longer be allowed to force its users to agree to the practically unrestricted collection and assigning of non-Facebook data to their Facebook accounts,' cartel office chief Andreas Mundt said.

Facebook said it would appeal the decision by the Federal Cartel Office, the culmination of a three-year probe, saying the antitrust watchdog underestimated the competition it faced, and undermined Europe-wide privacy rules that took effect last year.

'We disagree with their conclusions and intend to appeal so that people in Germany continue to benefit fully from all our services,' Facebook said in a blog post.

In its order, the cartel office said it would only be allowed to assign data from WhatsApp or Instagram to Facebook if users consented voluntarily. Collecting data from third-party websites and assigning it to Facebook would...