Up to 45,000 Irish Facebook users may have had their data improperly shared with consultancy Cambridge Analytica, the social media company confirmed.

In a blog post last night, the company’s chief technology officer Mike Schroepfer said the social media giant believed details on up to 87 million people may have have been improperly shared with the outside company. That was up from a previous media estimate of more than 50 million.

Facebook said its investigation showed the majority of users affected by the incident were in the US, with 97.1 per cent of those who installed the app at the centre of the scandal based primarily in the US.

More than 81 per cent of those affected – installers and their friends who may have had data collected – were in the US.

However, a number of Irish users are also believed to have been affected. While the number of Irish users who actually downloaded the app at the centre of the fiasco, yourdigitallife, was low – 15 people – others may have had their data taken because a friend based either here or in the US had downloaded the app.

Third-party developers

Facebook confirmed that the number of Irish people affected as a result could be as high as 44,687.

The company said it has taken a number of steps to change its practices in the wake of the revelations, including reducing the amount of data made available to third-party developers.

It has also disabled the ability to search the site for friends through email addresses and phone numbers, saying it believed users had data scraped in this way.

Facebook chief executive Mark Zuckerberg will testify about the matter next week before the US House energy and commerce committee, the panel said on Wednesday.

“We didn’t take a broad enough view of what our responsibility was and that was a huge mistake. It was my mistake,” Facebook chief executive Mark Zuckerberg said on Wednesday during a conference call with reporters. “We’re broadening our view of our responsibility.”

Privacy laws

Australia’s government also said it has started a formal investigation into whether Facebook breached the country’s privacy laws.

Mr Zuckerberg defended the company’s advertising business model, confirmed he wants to stay in charge and disclosed no “meaningful impact” from an online campaign by some users to delete their Facebook accounts.

He also defended gathering user data for a business model that lets advertisers use Facebook’s information and targeting tools to reach specific audiences.

“People tell us that, if they’re going to see ads, they want the ads to be good,” he said, noting that requires keeping track of what people are interested in.

Either way, he thinks he should remain at the helm of Facebook. “I think life is about learning from mistakes and figuring out what you need to do to move forward,” he said.

– Additional reporting by Bloomberg