Facebook has been fined a total of 110m euros (£95m) by the EU for providing “incorrect or misleading” information during the purchase of WhatsApp in 2014.
The European Commission said Facebook had said it could not automatically match user accounts on its own platform WhatsApp.
However, two years later it managed to do just that.
Facebook has said any errors made were not intentional.
In a statement, the Commission said: “The Commission has found that, contrary to Facebook’s statements in the 2014 merger review process, the technical possibility of automatically matching Facebook and WhatsApp users’ identities already existed in 2014, and that Facebook staff were aware of such a possibility.”
EU competition commissioner Margrethe Vestager said: “Today’s decision sends a clear signal to companies that they must comply with all aspects of EU merger rules, including the obligation to provide correct information.
“And it imposes a proportionate and deterrent fine on Facebook. The Commission must be able to take decisions about mergers’ effects on competition in full knowledge of accurate facts.”