British regulators are to investigate whether Facebook broke data protection laws by letting researchers conduct a psychological experiment on unknowing users.
The Information Commissioner's Office said it would be asking the social network questions and would also liaise with Irish regulators, as the company's European headquarters are in Dublin.
Although the regulator has not specified which laws the site may have infringed, it has the power to force companies to change their policies and can also issue fines up to £500,000 for breaching the Data Protection Act.
More top news
Binge drinking is costing British taxpayers £4.9 billion a year, a new study claims.
Details of thousands of peoples' medical records are being sold to fraudsters, it has been reported.
Britain is engaged in a "technology arms race" with terrorists determined to cause the country harm, the head of MI6 has warned.