European Union regulators have accused Microsoft of “possibly abusive” practices that violate the bloc’s competition rules by tying its Teams messaging and videoconferencing app to its widely used business software.

The European Commission said it is concerned the US tech giant has been “restricting competition” by bundling Teams with core office productivity applications such as Office 365 and Microsoft 365.

The commission, the 27-nation bloc’s top competition enforcer, said it suspects Microsoft might have granted Teams a “distribution advantage” by not giving customers a choice on whether to have Teams when they purchased the software.

The commission opened its investigation in July 2023 after rival Slack Technologies, which makes popular workplace messaging software, filed a complaint with Brussels.

The commission said that, while Microsoft has started offering some software packages without Teams, the changes are not enough to address its concerns and that it needs to do more to “restore competition”.

Microsoft president Brad Smith said in a prepared statement: “Having unbundled Teams and taken initial interoperability steps, we appreciate the additional clarity provided today and will work to find solutions to address the Commission‘s remaining concerns.”