Video report by ITV News Consumer Editor Chris Choi
Mark Zuckerberg has said it was "clearly a mistake" to trust Cambridge Analytica (CA) when Facebook asked the British data firm to delete tens of millions of users' data.
The Facebook founder said CA had provided formal assurances that data harvested from 50 million profiles had been destroyed after the breach was revealed in 2015.
"I don't know about you, but I'm used to when people legally certify that they are going to do something, that they do it. But I think this was clearly a mistake in retrospect," Zuckerberg told CNN.
The billionaire, who has been called on to give evidence to MPs in person over the scandal, said he would be happy to appear before US Congress "if it's the right thing to do".
The Facebook boss founder finally broke his silence earlier Wednesday posting a statement on the growing data scandal.
He admitted there was "a breach of trust" and his company had "made mistakes" in the wake of allegations made against CA.
The company had been suspended by Facebook amid claims it harvested personal details from more than 50 million users.
In his statement, Zuckerberg explained that in 2015, Facebook learned that a Cambridge University researcher named Aleksandr Kogan had shared data from his personality quiz app to a separate data firm, Cambridge Analytica.
Such an action was against Facebook's rules so they “demanded that Kogan and Cambridge Analytica formally certify that they had deleted all improperly acquired data. They provided these certifications.”
Zuckerberg continued: “Last week, we learned from The Guardian, The New York Times and Channel 4 that Cambridge Analytica may not have deleted the data as they had certified. We immediately banned them from using any of our services.
“Cambridge Analytica claims they have already deleted the data and has agreed to a forensic audit by a firm we hired to confirm this. We're also working with regulators as they investigate what happened.”
"This was a breach of trust between Kogan, Cambridge Analytica and Facebook. But it was also a breach of trust between Facebook and the people who share their data with us and expect us to protect it. We need to fix that."
Zuckerberg outlined several reforms to repair trust in the social media platform.
The company will ban any developer that does not agree to a thorough audit.
Data will be generally limited to your name, profile photo and email address.
Developers will no longer have access to data from people who have not used an app in three months.
A tool will be visible at the top of the News Feed showing which apps have permission to your data.
Cambridge Analytica played a key role in mapping out the behaviour of voters in the run-up to the 2016 US election and was also used during the EU referendum campaign earlier that year.
The chief executive of Cambridge Analytica, Alexander Nix, was suspended on Tuesday after Channel 4 News broadcast Nix boasting about his firm's role in the Trump presidential campaign.
He said Cambridge Analytica handled "all the data, all the analytics, all the targeting" and used emails with a "self-destruct timer" to make it difficult for authorities to trace a paper trail.
Authorities in Britain and the United States are now investigating the alleged improper use of Facebook data.