Mark Zuckerberg apologised for a "major breach of trust" with two billion users of Facebook and vowed to take steps to protect user data, as the social media giant was rocked by a data breach scandal.
In his first public comments on the uproar over harvesting of data of 50 million users by a British firm linked to Donald Trump's 2016 presidential campaign, the Facebook CEO admitted of making "mistakes" and said he was "happy" to answer questions about the scandal before US Congress.
"This was a major breach of trust and I'm really sorry that this happened," he told CNN.
"Our responsibility now is to make sure this doesn't happen again," he said.
He said Facebook has already taken important steps to prevent such a situation from happening again.
He said the site would be reviewing thousands of apps in an "intensive process".
The data scandal erupted after a whistleblower revealed that Cambridge Analytica, a data firm with ties to Trump's 2016 campaign, accessed personal data from 50 million Facebook users without their knowledge, and might have kept that data even after Facebook told the company to delete it.
Cambridge Analytica (CA) had created psychological profiles on 50 million Facebook users via a personality prediction app, created by a researcher named Aleksandr Kogan.
Earlier, Zuckerberg, 33, through a lengthy Facebook post, addressed the privacy scandal. He wrote that the company made "mistakes" and outlined how it has changed its policies to make sure that user data is protected.
"I started Facebook, and at the end of the day, I'm responsible for what happens on our platform. I'm serious about doing what it takes to protect our community," he said.
Zuckerberg said Facebook has a "responsibility" to protect its users' data and if it fails, "we don't deserve to serve you."
He acknowledged that there is more the company needs to do.
"...But we also made mistakes, there's more to do, and we need to step up and do it," he said.
Zuckerberg said Facebook plans to alert everyone whose data was accessed by Cambridge Analytica. But he added that he wishes the company had not waited so long to tell people what happened.
"That's definitely something that, looking back on this, I regret that we didn't do at the time," he told CNN. "I think we got that wrong."
And he said he's made other mistakes along the way.
"I started this when I was so young and inexperienced," Zuckerberg said. "I made technical errors and business errors. I hired the wrong people. I trusted the wrong people," he said.
He said the company will "investigate every app that has access to a large amount of information from before we locked down our platform, and if we detect any suspicious activity, we're going to do a full forensic audit."
"We're going to review thousands of apps," he said.
Facebook said it discovered last week that CA may not have deleted the data as it certified.
"We should not have trusted Cambridge Analytica's certification, and we are not going to make that mistake again," Zuckerberg said.
"This was a breach of trust between Kogan, Cambridge Analytica and Facebook," Zuckerberg wrote in the post. "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."
In a damage control mode, Zuckerberg announced a slew of measures aimed to secure the platform further.
For this, the Facebook founder said, his company will take three steps to prevent the data misuse.
"We will investigate all apps that had access to large amounts of information before we changed our platform to dramatically reduce data access in 2014, and we will conduct a full audit of any app with suspicious activity," he said.
"We will ban any developer from our platform that does not agree to a thorough audit. And if we find developers that misused personally identifiable information, we will ban them and tell everyone affected by those apps," he added.
Zuckerberg said that the second step is to restrict developers' data access even further to prevent other kinds of abuse.
He cited an example for this: "It (Facebook) will remove developers' access to one's data if the app hasn't been used by the person in three months."
"We will reduce the data you give an app when you sign in -- to only your name, profile photo, and email address. We'll require developers to not only get approval but also sign a contract in order to ask anyone for access to their posts or other private data. And we'll have more changes to share in the next few days," Zuckerberg said.
He said next month Facebook will show everyone a tool at the top of their News Feed with the apps they have used and an easy way to revoke those apps' permissions to their data.
"We already have a tool to do this in your privacy settings, and now we will put this tool at the top of your News Feed to make sure everyone sees it, Zuckerberg said.
Over the past several days, Facebook has been facing an investigation by the Federal Trade Commission and calls for legislative testimonies in the US and Europe.
India's IT and Law Minister Ravi Shankar Prasad has warned social media companies such as Facebook of stringent actions if there was any attempt to influence the electoral process of any country.
Amidst a global outrage against Facebook, the Silicon Valley-based company, which currently has 2 billion monthly active users, has suffered a loss of USD 50 billion in market value