In a statement on its website, the German Cartel Office said, "The authority is investigating suspicions that with its specific terms of service on the use of user data, Facebook has abused its possibly dominant position in the market for social networks."

According to Cartel Office head Andreas Mundt, user data was "highly important" for companies like Facebook, which relied on advertizing for its finances.

Users wanting to use Facebook have to agree to the network's collection and use of their data by accepting the company's terms of service. Cartel Office experts believed it was difficult for Facebook members to understand and assess these terms.

"There is considerable doubt as to the admissibility of this procedure, in particular under applicable national data protection law," the Cartel Office said on Wednesday. If investigators managed to establish a link between data infringement and Facebook's dominant market position, it could constitute an abusive practice under Germany's competition law, the statement said.

Political leaders have criticized Zuckerberg's company for failing to act against xenophobic content

Investigators will examine whether there was a connection between Facebook's prominent market presence and misuse of data. Cartel officials said they would work "in close contact with the competent data protection officers, consumer protection associations as well as the European Commission and the competition authorities of the other EU member states."

Facebook to cooperate

The announcement came shortly after Facebook chief Mark Zuckerberg came to Germany in a high-profile visit to talk with politicians about dealing with xenophobic content on the social network.

Responding to news about the probe, a Facebook spokeswoman said, "We are confident that we comply with the law and we look forward to working with the Federal Cartel Office to answer their questions."

Facebook is the world's largest social network. Chinese internet portal Tencent's QQ comes a distant second. Nearly 84 percent of Facebook's users are outside the United States and Canada. The company also owns WhatsApp, Facebook Messenger and picture-sharing application Instagram.

mg/sms (Reuters, AFP)