Facebook has been fined €150,000 (NZ$240,000) by French authorities for "unfair tracking" of its users following a pan-European investigation into the internet giant.
The fine is the latest clash between Facebook and European authorities, which have repeatedly criticised its use of personal data.
CNIL, the French data regulator, along with its counterpart in the Netherlands, slammed Facebook for breaking EU rules.
The authorities, as well as Spanish and German regulators, have spent years investigating whether it informed users about how it was collecting data.
CNIL said that Facebook collected and compiled user data "without having a legal basis" and "without obtaining their explicit consent". It said the social network was able to track websites that users were visiting when they left Facebook, and that this was unclear to the users themselves.
The Dutch data authority said Facebook had targeted adverts based on sensitive subjects such as their sexual preference.
Unlike the French regulator, it did not fine the company, saying that Facebook had made changes, but warned that it may still impose sanctions.
While the sums involve amount to a rounding error in Facebook's profits, the combative stance from regulators may trouble it ahead of stricter European data laws coming into force next year.
The incoming General Data Protection Regulation will mean companies can be fined up to 4pc of their global revenues - in Facebook's case around US$1.1b (NZ$1.6m) - can be levied by authorities.
The authorities did not demand that Facebook make particular changes. The company said it obeys EU data protection law and that it had made changes recently to be more transparent, but did not say if it would appeal the fine.
"We take note of the CNIL's decision with which we respectfully disagree. We value the opportunities we've had to engage with the CNIL and reinforce how seriously we take the privacy of people who use Facebook," it said.
"Facebook has long complied with EU data protection law through our establishment in Ireland. We remain open to continuing to work on these issues with the CNIL, as we prepare for the EU's new data protection regulations in 2018."