Washington (Web Desk): Facebook claimed that personal data on about 87 million users was improperly shared with British political consultancy Cambridge Analytica, internal media reported.

The announcement came as Facebook unveiled clearer terms of service to enable users to better understand data sharing, and as a congressional panel said chief executive Mark Zuckerberg would appear next week to address privacy issues.

The new figure eclipses a previous estimate of 50 million in a further embarrassment to the social network roiled by a privacy scandal.

Facebook’s chief technology officer Mike Schroepfer released the new figures on affected users as he discussed implementation of new privacy tools for users of the huge social network.

“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,” he said.

Zuckerberg will likely face multiple congressional hearings as his social media giant battles a firestorm following revelations that the British consulting firm Cambridge Analytica obtained the data of 50 million Facebook users to try and manipulate US voters in the 2016 presidential election.

The Facebook co-founder has also been invited to appear before the Senate’s Judiciary Committee on April 10, alongside Google chief Sundar Pichai and Twitter head Jack Dorsey.