Facebook faces fresh questions over when it knew of data harvesting

Allegations come as US prosecutors investigate claims of cover-up

Facebook is facing explosive new questions about when senior executives knew of Cambridge Analytica's abuse of users' data, one year on from when the scandal first broke, as federal prosecutors investigate claims that the social media giant has covered up the extent of its relationship with the firm.

The Observer has also learned of claims that a meeting was hosted at the office of Facebook board member and confidant of its CEO Mark Zuckerberg, Marc Andreessen with Christopher Wylie, the Cambridge Analytica whistleblower, in the summer of 2016 just as the data firm started working for the Trump campaign.