Facebook has said it now believes up to 87 million people’s data was improperly shared with the political consultancy Cambridge Analytica – many more than previously disclosed.
The BBC has been told that about 1.1 million of them are UK-based.
The overall figure had been previously quoted as being 50 million by the whistleblower Christopher Wylie.
The details were revealed in a blog by the tech firm’s chief technology officer, Mike Schroepfer.
The BBC has also learned that Facebook now estimates that about 305,000 people had installed the This Is Your Digital Life quiz that had made the data-harvesting possible. The figure previously suggested had been 270,000.