A leading newspaper reported that in 2015, an email exchange between Facebook and Cambridge Analytica shows both companies responded to early indications that the data firm was misusing the social media giant's data.
Previously, Zuckerberg said that he was sorry about the Cambridge Analytica scandal affecting "tens of millions" and that he would be "willing to testify before the US Congress."
Cambridge Analytica, a London-based data analytics firm, was accused of harvesting private information from the Facebook profiles of more than 50 million users without their permission and using the data to help politicians, including US President Donald Trump and the Brexit campaign.