Facebook Chief Executive Mark Zuckerberg apologized to U.K. users for the Cambridge Analytica data leak scandal through full-page advertisements in British newspapers on Sunday.
“You may have heard about a quiz app built by a university researcher that leaked Facebook data of millions of people in 2014.
This was a breach of trust and I’m sorry we didn’t do more at the time,” Zuckerberg wrote in the ad.
He said Facebook already stopped similar apps from getting so much information and is limiting the data apps can get when users sign in using their Facebook account.
But he warned the app used by Cambridge Analytica was likely not the only one to have had access to a large amount of Facebook users’ information before the company tightened up its procedures.
“We expect there are others,” he said, noting that Facebook was investigating every single app that had access to large amount of data “before we fixed this.”
Zuckerberg promised the platform will ban the apps when it finds them and inform all affected users.
“Thank you for believing in this community. I promise to do better for you,” he wrote.
Both Cambridge Analytica and the academic who made the controversial app have denied wrongdoing.
Facebook has 44 million users in the U.K., putting the country in top 10 in the world for the number of Facebook users, according to data from Statista published by Deutsche Welle.
Věra Jourová, the European commissioner for justice and consumers, told German media outlet Bild am Sonntag that the misuse of data from 50 million Facebook users “is completely unacceptable” and demanded the social media company clarify how many European users have been affected by it.