German antitrust authorities have issued a ruling prohibiting Facebook from combining user data from different sources.

The Bundeskartellamt says Facebook users have only been able to use the social network on the condition that it can collect user data “outside of the Facebook website in the internet or on smartphone apps and assign these data to the user's Facebook account". This includes assigning data from Facebook-owned services like WhatsApp and Instagram, as well as third-party websites, to a Facebook user account.

Bundeskartellamt president Andreas Mundt said on Thursday that the ruling means that "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 user accounts."

Facebook said it rejects the decision, and will appeal.