Facebook is changing the access third-party applications have to data on its platform, according to a public statement from Zuckerberg. 

The company will investigate apps that had access to data and user information prior to a change to the platform in 2014 which reduced data access for developers, conducting an audit of any app with "suspicious activity". It will also restrict developers’ access further and make it easier for users to understand which apps have access to their data.

The company banned the personality survey app developed by researcher Aleksandr Kogan from its platform in 2015, after it learned from journalists at the Guardian that Kogan had shared data from the app with Cambridge Analytica, according to Zuckerberg. At the time, Facebook asked Kogan and Cambridge Analytica to provide formal certification that the data had been deleted, which Facebook says they did provide.

He acknowledged Facebook’s role in the breach, saying: “We have a responsibility to protect your data, and if we can't then we don't deserve to serve you.

“The most important actions to prevent this from happening again today we have already taken years ago. But we also made mistakes, there’s more to do, and we need to step up and do it.”

He described events as a “breach of trust between Kogan, Cambridge Analytica and Facebook”, but also said a breach of trust had occurred between Facebook and its users.

Zuckerberg said he was “serious” about tackling the issue of data privacy on the platform, adding: “While this specific issue involving Cambridge Analytica should no longer happen with new apps today, that doesn't change what happened in the past. We will learn from this experience to secure our platform further and make our community safer for everyone going forward.”