Massive compilation of personal data..
The watchdog - the National Commission on Informatics and Liberties (CNIL) - said the tech giant has a "massive compilation of personal data" for targeted advertising "without a legal base".
"It has also been noticed that Facebook collected data on browsing activity of internet users on third-party websites, via the “datr” cookie, without their knowledge," it said.
Reportedly, Facebook is also being investigated by Belgium, the Netherlands, Germany and Spain for data privacy violations.
Facebook 'respectfully' disagrees..
Facebook said: “We take note of the CNIL’s decision with which we respectfully disagree.
"At Facebook, putting people in control of their privacy is at the heart of everything we do.
"Over recent years, we’ve simplified our policies further to help people understand how we use information to make Facebook better.”
The French watchdog gave facebook a deadline last year to stop tracking non-users’ web activity without their consent, and an order to stop some transfers of personal data to the US.
Facebook has argued that it is the Irish data protection authority, not the CNIL or any other EU data regulator, was the competent authority to formulate such orders, as the social media company’s European headquarters are located in Dublin.
FB shares lost 0.5% to stand at $149.46.