Facebook says 87 million may be affected by data breach

Mark Zuckerberg agrees to testify before a US congressional panel April 11 as Facebook faces pressure over a massive hijacking of private user data (Courtesy)

Facebook said Wednesday the personal data of up to 87 million users was improperly shared with British political consultancy Cambridge Analytica, as Mark Zuckerberg defended his leadership at the huge social network.

Facebook's estimate was far higher than news reports suggesting 50 million users may have been affected in the privacy scandal which has roiled the company and sparked questions for the entire internet sector on data protection.