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In an odd twist, Facebook's WhatsApp messaging app -- which won applause last year when it turned on end-to-end encryption by default -- is being sued in German court over privacy concerns related to the way it collects and shares data with Facebook.

That's because in August, WhatsApp changed its terms and privacy policy, saying it would coordinate more with parent company Facebook, allowing WhatsApp "to do things like track basic metrics about how often people use our services and better fight spam on WhatsApp," the messaging company wrote in a blog post. "And by connecting your phone number with Facebook's systems, Facebook can offer better friend suggestions and show you more relevant ads if you have an account with them."

Privacy advocates in the European Union weren't amused.

In September, the Hamburg Commissioner for Data Protection and Freedom of Information ordered Facebook to stop collecting and storing WhatsApp data from Germany's 35 million users. In December, the European Commission sent a statement of objections to Facebook alleging the world's largest social network gave "incorrect or misleading information" about the possibility of linking users' accounts during a 2014 review of its $19 billion acquisition of WhatsApp.

Now the Federation of German Consumer Organizations (Verbraucherzentrale Bundesverband, or VZBV) is asking the Berlin county court for an injunction to stop the data sharing, and to force Facebook to delete any data WhatsApp has given it. The VZBV accused the companies of abusing users' trust.

WhatsApp's "privacy policy and terms updates comply with applicable law," the company said in an emailed statement. "The updates also comply with guidelines issued by EU regulators. As ever we remain open to working collaboratively to address their questions."

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