Facebook has been fined €110m (£94.5m) by EU competition regulators in relation to its takeover of WhatsApp.
Officials said the penalty was being imposed after the social network was found to have given "incorrect or misleading" information in 2014.
The European Commission said Facebook had informed its anti-trust body, in submissions ahead of the $19bn (£15.3bn) buyout, it would be unable to "establish reliable automated matching" between Facebook and WhatsApp user accounts.
But it determined that the mobile messaging service offered updates in 2016, after the deal had been completed, that included the possibility of linking user phone numbers with Facebook user IDs.
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.
"The Commission must be able to take decisions about mergers' effects on competition in full knowledge of accurate facts."
Facebook indicated that it did not intend to fight the penalty.
A spokesperson said: "We've acted in good faith since our very first interactions with the Commission and we've sought to provide accurate information at every turn.
"The errors we made in our 2014 filings were not intentional and the Commission has confirmed that they did not impact the outcome of the merger review.
"Today's announcement brings this matter to a close."