Germany has ordered the Social media giant to stop collecting and storing data on WhatsApp users in Germany  marking it the first regulatory challenge related to the data-sharing scheme that Facebook announced in August.

Germany’s privacy watchdog said that sharing WhatsApp user data with Facebook, constitutes “an infringement of national data protection law.” The regulatory body also ordered Facebook to delete all data that has already been transferred from WhatsApp.

The data sharing allows Facebook to deliver more targeted advertising and friend suggestions, and that analytics data will help combat spam and fraud.

However, privacy advocates have criticized the companies for not being transparent about the change.

Johannes Caspar, the Hamburg data protection commissioner, echoed those concerns in a statement on Tuesday, saying that Facebook has not “obtained effective approval” of the policy change from WhatsApp users.

Caspar also expressed concern that Facebook may eventually seek to collect data on a broader range of users, including those listed in WhatsApp contacts lists who are not connected to Facebook.

A Facebook spokesperson has revealed that they will appeal the order from Germany’s privacy watchdog, insisting that Facebook complies with EU data protection law.