German Minister of Justice Katarina Barley delivers a speech at the 60th annual meeting of the German Civil Service Federation | Sascha Steinbach/EPA-EFE German minister and MEP candidate goes after Facebook Top social democrat warns of Facebook messaging monopoly

German Justice Minister Katarina Barley has slammed tech giant Facebook — again — warning the company may be attempting to create a messaging monopoly.

Barley, a social democrat, is her party’s top candidate for the European Parliament election in May and therefore guaranteed to win a seat. “If Facebook is combining [its own] messengers, this is an attempt to create a monopoly,” Barley said, referring to the company’s plan to integrate Messenger, WhatsApp and Instagram.

In an exclusive interview with POLITICO, Nick Clegg, Facebook’s global head of public affairs, confirmed Monday that the company was looking at how to make its messaging services interoperable under one data architecture.

“What Facebook is planning is making a mockery of the idea of interoperability,” Barley said. The concept should instead be “about allowing users of smaller and more secure messengers to send messages to WhatsApp users, for instance.”

Barley’s intervention is not her first Facebook criticism. Last week, she called for Facebook to do more to fight hate speech and protect users’ data in response to an article written by the social media giant’s chief executive Mark Zuckerberg. A month earlier, she told POLITICO she expects the company to “immediately” address allegations about its practice of sharing data with other companies, and “to cooperate with data protection authorities.”

During an earnings call, Zuckerberg confirmed reports that the company was considering merging its messenger services but said the move would not be completed this year.

Barley isn’t the only one going after Facebook. A German regulator is also trying to gather support from other EU countries to reassert a ruling that deemed data sharing between WhatsApp and Facebook unlawful.