Facebook is facing questions about whether it has violated data-protection laws in the UK.
The British data watchdog is investigating the social media site for having allowed researchers to conduct a psychological experiment on its users.
The study – two years ago – involved nearly 700,000 unwitting users.
It was to see if Facebook could alter the emotional state of users and prompt them to post either more positive or negative content..
Facebook has acknowledged it upset many people but insists there was full protection for their personal information.
“We’re aware of this issue and will be speaking to Facebook, as well as liaising with the Irish data protection authority, to learn more about the circumstances,” the Information Commissioner’s Office said.
The company’s European headquarters is in Ireland.
The Commissioner’s Office monitors how personal data is used and has the power to force organisations to change their policies and can levy fines of up to 500,000 pounds (628,000 euros).