MercoPress. South Atlantic News Agency

Zuckenberg admitted the network “made mistakes”, and was willing to testify before Congress

In a statement Zuckerberg admitted a “breach of trust” occurred and with CNN said he was “really sorry”, and pledged action against “rogue apps”.

Facebook founder Mark Zuckerberg has admitted that the social network “made mistakes” that led to millions of Facebook users having their data exploited by a political consultancy.Cambridge Analytica is accused of improperly using the data on behalf of political clients. In a statement Zuckerberg said a “breach of trust” had occurred. In a later interview with CNN he said he was “really sorry”, and pledged to take action against “rogue apps”.

 He added that he was “happy” to testify before Congress “if it's the right thing to do”.

In his statement posted on Facebook, he promised to make it far harder for apps to “harvest” user information.

“We have a responsibility to protect your data, and if we can't then we don't deserve to serve you,” Mr Zuckerberg said.

To address current and past problems, Mr Zuckerberg said his company would:

-investigate all Facebook apps that had access to large amounts of information before the platform was changed “to dramatically reduce data access” in 2014

 - conduct a “full forensic audit” of any app with suspicious activity

- ban any developer that did not agree to a thorough audit

-ban developers that had misused personally identifiable information, and “tell everyone affected by those apps”

In future, he said Facebook would:

- restrict developers' data access “even further” to prevent other kinds of abuse

- remove developers' access to a user's data if the user hadn't activated the developer's app for three months

-reduce the data that users give an app when they sign in to just name, profile photo, and email address

- require developers to obtain approval and also sign a contract in order to ask anyone for access to their posts or other private data

Mr Zuckerberg added: “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.”

In 2014, Facebook invited users to find out their personality type via a quiz developed by Cambridge University researcher Dr Aleksandr Kogan called This is Your Digital Life.

About 270,000 users' data was collected, but the app also collected some public data from users' friends.

Facebook has since changed the amount of data developers can gather in this way, but a whistleblower, Christopher Wylie, says the data of about 50 million people was harvested for Cambridge Analytica before the rules on user consent were tightened up.

Mr Wylie claims the data was sold to Cambridge Analytica - which has no connection with Cambridge University - which then used it to psychologically profile people and deliver pro-Trump material to them.