Microsoft has been issued with a formal antitrust warning from the European Union concerning its proposed acquisition of Activision Blizzard.

Sources told Politico a statement of objections was sent to the Xbox firm on Tuesday, in which the European Commission’s antitrust enforcers detailed their concerns over the $68.7 billion deal.

While the details of this statement are unknown, the Commission has previously said it would need to investigate the deal thoroughly because the merger “may significantly reduce competition on the markets for the distribution of console and PC video games, including multi-game subscription services and/or cloud game streaming services, and for PC operating systems.”

The EC was particularly concerned about Microsoft withholding Call of Duty and other Activision Blizzard products from other consoles, and that the deal could also harm competition in the games subscription and cloud gaming spaces.

Microsoft has responded to the report, telling Politico it is committed to “finding a path forward” for the merger.

“We are listening carefully to the European Commission’s concerns and are confident we can address them,” a spokesperson told the site.

The EC’s investigation began in November, with a deadline of March 23 for the final decision.

Microsoft has already assured regulators it will continue to release Call of Duty on other consoles, even promising ten years of the franchise on Switch and Steam, and promising a similar deal for Sony – although PlayStation CEO Jim Ryan has since told GamesIndustry.biz this offer was “inadequate on many levels.”

Microsoft’s proposed acquisition of Activision Blizzard also faces a legal complaint from the Federal Trade Commission in the US, and an in-depth investigation by the UK’s Competition and Markets Authority.

You can follow the many regulatory hurdles it faces in our extensive primer.