Update at foot of post.
Reuters cites “two people familiar with the matter” as its source, in a move that could see European regulatory bodies extend its investigations into the company.
Whilst the European Commission hasn’t confirmed this, and Microsoft has declined to comment saying that it wouldn’t issue a statement on “rumors or speculation”, this is a significant move if it proves true and will serve to heighten tensions between the two companies which have been escalating over recent months.
Whilst this led to a series of public retaliations between the two companies, if the Redmond-based company has lodged a formal complaint against Google overs its social network, this would certainly takes things to the next level.
Update: Speaking to ZDnet, Microsoft has denied being part of any antitrust complaint related to Google+. However, that does not discount the possibility of Reuters being partially right, and others being involved in a complaint.