Facebook worker says 87 million users’ data was shared

Facebook has revealed that the personal data of up to 87 million people may have been improperly shared with political consultancy Cambridge Analytica, far more than previously thought.

Earlier estimates had suggested about 50 million users were affected by the scandal involving the Trump-affiliated company, which is said to have gathered the information with the intent of swaying elections.

Mark Zuckerberg, the chief executive, admitted on Wednesday that the social network had not taken a broad enough view of its responsibility in the world, calling it a “huge mistake. It was my mistake,” he said.

“Knowing what I know today, clearly we should have done more.”

But he insisted that he was still the best person to lead the company he founded.

Congressional officials in the US said Mr Zuckerberg will testify about the matter on Tuesday and Wednesday.

British members of parliament have written a further letter requesting him to appear before Parliament’s Digital, Culture, Media and Sport Committee. Facebook had said it would send two of his deputies.

The latest developments came as the social media giant announced plans to restrict the personal data that outsiders can access in the wake of the scandal.

Facebook acknowledged in March that the personal information of millions of its users had ended up in the hands of Cambridge Analytica.

Shares in the tech giant have fallen by more than 16 per cent since then, as world leaders and policymakers have lined up to call for more regulation of social media after the revelations.

Investigations by The New York Times and Observer newspapers had led to the earlier estimate of about 50 million affected Facebook users.

But on Wednesday, Mike Schroepfer, Facebook’s chief technology officer, wrote in a blog post that the data of as many as 87 million people had been shared. Most of them were in the US, he said.

Facebook said it reached the higher figure by taking the 270,000 people who had downloaded a personality quiz app created by researcher Aleksandr Kogan and then adding in the number of friends they had at the time.

This personal information was then passed on to Cambridge Analytica, which said it had engaged Mr Kogan “in good faith” to collect Facebook data. Facebook says the move was against its rules.

“We didn’t take a broad enough view of what our responsibility was,” Mr Zuckerberg said. “We’re broadening our view of our responsibility.”

London-based Cambridge Analytica, which worked for Donald Trump’s 2016 presidential campaign, insisted the number of affected users was far lower than Facebook’s estimate.

In a Twitter post on Wednesday, it insisted again that it had deleted all the data.

“When you’re building something like Facebook that is unprecedented in the world, there are going to be things that you mess up,” Mr Zuckerberg said. It was important to learn from mistakes, he said.

But he said he was unaware of any conversations among Facebook board members to oust him. “I’m not looking to throw anyone else under the bus for mistakes that we made here,” he said.

Mr Zuckerberg said a campaign urging users to delete their Facebook accounts, has had no “meaningful impact” on the company.

He also defended the practice of gathering user data as part of a business model enabling advertisers to target specific audiences.