Speaking to National Public Radio and NBC's "Today Show" on Thursday and Friday, she said Facebook 'did not do enough to protect people's data'.

"We know that we did not do enough to protect people's data," Sandberg told NPR.

"I'm really sorry for that. Mark (Zuckerberg) is really sorry for that, and what we're doing now is taking really firm action.

"Safety and security is never done, it's an arms race. You build something, someone tries to abuse it," Sandberg added.

"But the bigger [question] is, 'Should we have taken these steps years ago anyway?' And the answer to that is yes.

"We really believed in social experiences, we really believed in protecting privacy, but we were way too idealistic.

"We did not think enough about the abuse cases and now we're taking really firm steps across the board," she said.

Speaking about Cambridge Analytica gaffe, she said, "When we received word that this researcher gave the data to Cambridge Analytica, they assured us it was deleted. We did not follow up and confirm, and that's on us - and particularly once they were active in the election, we should have done that."

Earlier this week, Facebook said that over 87 million user accounts were compromised due to a data breach.

"In total, we believe the Facebook information of up to 87 million people — mostly in the US — may have been improperly shared with Cambridge Analytica," Mike Schroepfer, Facebook's Chief Technology Officer, shared in a post.

Meanwhile, contrary to Facebook's admission,Cambridge Analytica said 30 million individuals data have been obtained.

"Cambridge Analytica licensed data from GSR for 30 million individuals, not 87 million. We did not receive more than 30 million records from research company GSR," it tweeted.

Sandberg told the Today Show that the company is now 'going after fake accounts'.

"We're going after fake accounts. A lot of it is politically motivated but even more is economically motivated," she said.

After the saga unfolded, Facebook founder Mark Zuckerberg had apologised, but that did not prevent his company from losing billions.

According to reports, Facebook lost around USD 58 billion in the month of March.

Decoding Facebook's huge loss, senior analyst Laith Khalaf told BBC, "One of the secrets of Facebook's success has been that the more people who use Facebook, the more integral it becomes to its customers. Unfortunately for Facebook, the same dynamic cuts in the opposite direction if it loses a meaningful number of users as a result of this scandal."

Image: World Economic Forum/Wikipedia