BERLIN (AP) — Germany's cartel office says Facebook is acting in an abusive fashion by collecting data on the way people use third-party websites.

The cartel office said Tuesday its investigation of Facebook reached the preliminary conclusion that the company has a dominant position in the market for social networking sites in Germany.

Further, it said that Facebook is "acting abusively" by only allowing people to use its social network if they consent to the collection of all types of user data from third party sites and subsidiaries such as WhatsApp or Instagram.

Creating custom profiles of users and selling them to advertising clients is a central pillar of Facebook's business model.

Facebook can now respond before authorities make a final decision, likely after the middle of next year.