Official charges, known as a Statement of Objections, have been filed against Facebook, with a potential fine of up to one per cent of profits if the complaint is upheld. Facebook has until 31 January to formally respond to the antitrust charges.
An investigation by the European watchdog found that the social network provided "incorrect or misleading information" during its investigation into its takeover of WhatsApp, approved in 2014.
"Companies are obliged to give the Commission accurate information during merger investigations. They must take this obligation seriously," said competition commissioner Margrethe Vestager.
"Our timely and effective review of mergers depends on the accuracy of the information provided by the companies involved. In this specific case, the Commission's preliminary view is that Facebook gave us incorrect or misleading information during the investigation into its acquisition of WhatsApp. Facebook now has the opportunity to respond."
The response was just one of the factors taken into consideration in giving the deal the green light.
“We respect the Commission's process and are confident that a full review of the facts will confirm Facebook has acted in good faith," said a Facebook spokesperson.