Facebook indicated in a blog post yesterday that information of up to 87 million people – 37 million more than originally revealed – may have been improperly shared with Cambridge Analytica.

Facebook also reported that this may have included data of more than 300,000 Australians. The company’s chief technology officer, Mike Schroepfer, said the company would make major changes to the way third-parties can access data on the platform. He also said users would be informed if their information could have been improperly shared with Cambridge Analytica.

Cambridge Analytica has disputed the revised figure, saying it licensed data for no more than 30 million accounts.

The disclosure comes in the wake of Facebook founder and CEO Mark Zuckerberg agreeing to testify before the United States Congress in the wake of public outcry over the scandal.

In an interview with Vox on Monday, Zuckerberg discussed changes the company was making to its governance practices, and how it was responding to ‘fake news’ and abuses of its platform, seen in the use of Russian-managed pages and accounts on Facebook and Facebook-owned Instagram to influence the 2016 US Presidential Election.

Zuckerberg, who is CEO and holds a controlling amount of voting shares in Facebook, has significant personal power. Asked to comment on whether, as a result, the governance structure makes him less accountable, Zuckerberg acknowledged the company had failed in the past to be transparent about issues on the platform.

The saga provides insight into the challenges facing company leadership, particularly in the technology sphere. Public trust in Facebook has taken a major blow in the past few weeks, with the company seeing a drop in value on the stock market of nearly USD$80 billion since the story first broke.

As a result of the information concerning Australian accounts, Australia’s acting privacy and information commissioner today also announced that her office is opening an investigation into whether Facebook has breached Australia’s privacy laws.

Zuckerberg is due to testify before a joint hearing of the Senate Judiciary and Commerce, Science and Transportation Committees on 10 April, followed by the House Energy and Commerce Committee on 11 April.