Facebook CEOr Mark Zuckerberg said that he made a "huge mistake" in not focusing more on potential abuse of users' personal information, as the social media giant he founded revealed that data breaches were far more extensive than previously known, according to a report from the Dow Jones Newswires made available to EFE Thursday. 

Zuckerberg's most direct mea culpa to date came as Facebook disclosed Wednesday that data from as many as 87 million of its users may have been improperly shared with an analytics firm tied to the 2016 campaign of President Donald Trump, up from the 50 million previously reported. It said about 70.6 million of the users were in the U.S. 

Facebook released the higher figure in a statement laying out several updates to its service intended to better protect the privacy of users and increase their control over how their information is shared. 

In Australia, where Facebook put the number of affected users at 311,000, the privacy watchdog said Thursday that it is investigating whether privacy laws had been breached. 

In another revelation, the company said "most people on Facebook" could have had information scraped by marketers who used a feature that distributed profile data connected to users' email addresses and phone numbers.

Facebook said it has now disabled the feature. 

The disclosures came as the company is stepping up its efforts to repair trust with regulators and the public in the wake of several controversies tied to the election. 

Zuckerberg's remarks, made in a conference call with reporters, served as a trial run of sorts for his testimony on Capitol Hill next week, where the 33-year-old billionaire is expected to be grilled on how the company handles its customers' data. 

Facebook has about 239 million monthly users in the U.S. and Canada, and 3.2 billion monthly users worldwide. 

Facebook has come under heavy criticism after it was revealed earlier this year that the analytics firm, Cambridge Analytica, obtained Facebook user information on tens of millions of users. It also faces questions over the proliferation of "fake news" and the presence of Russian operatives on the service during the race. 

In the conference call, Zuckerberg said he erred when he dismissed the threat of fake news as "crazy" shortly after the 2016 election. "What is clear at this point is that it was too flippant," Zuckerberg said. 

 He called Facebook "an idealistic and optimistic company," and suggested it might have more disclosures to make soon. "We're going to keep on looking for things, we're going to keep on finding more, and we'll update you then," he said. 

Zuckerberg will testify before Senate and House panels next week. Late Wednesday two Senate committees announced a joint hearing on April 10 where Zuckerberg will appear as the sole witness. The hearing before the Senate Commerce Committee and the Senate Judiciary Committee will focus on social media and the use and abuse of user data, according to a release. 

Senate Commerce Committee Chairman John Thune (R., S.D.) said the hearing will be "a public conversation with the CEO of this powerful and influential company about his vision for addressing problems that have generated significant concern about Facebook's role in our democracy, bad actors using the platform, and user privacy." 

"This hearing will explore approaches to privacy that satisfy consumer expectations while encouraging innovation," said Sen. Chuck Grassley (R., Iowa), the Judiciary Committee chairman, in a statement. 

Zuckerberg is scheduled to appear the next day, on April 11, before the House Energy and Commerce Committee, which oversees many telecommunications and internet policy issues. The hearing will focus on "the company's use and protection of user data," the panel said in its announcement, but lawmakers can also press Zuckerberg on other matters, according to the Dow Jones report. 

The Senate and House hearings are expected to place Zuckerberg in the kind of unpredictable spectacle he has largely avoided.

His public appearances, in internal gatherings with employees or during his tour of America last year, have often been tightly scripted. Zuckerberg recently declined to appear before a United Kingdom parliamentary committee seeking evidence on how companies acquire user data from Facebook, choosing to send a deputy instead. 

Zuckerberg's first public testimony before Congress would mark a pivotal moment for the 14-year-old company. 

A series of revelations over the past year has shaken user trust in Facebook's products. On March 16, Facebook acknowledged that user data was improperly obtained by Cambridge Analytica.

Six months before that, Facebook disclosed that it had been exploited by Russian-backed propagandists in an attempt to sow divisions in the U.S. 

Facebook has taken steps to address criticisms from its users, regulators, and lawmakers. On Tuesday, it announced that it had identified and removed a new batch of 135 accounts on its site linked to Russia's Internet Research Agency troll farm. 

To address concerns about privacy, the social network is releasing greater detail about how it collects and deploys vast troves of information about users, proposing revisions to its terms of service and data policy on Wednesday. The documents mark the company's first major update to its privacy disclosures since 2015. 

The proposed policies don't ask users for new permissions or change the preferences they have set in the past, but instead lay out more information about how the network operates. The documents describe how Facebook deploys user data to customize the posts and ads users see and the circumstances under which it shares data, among other things. The revised terms also remind users that Facebook shares information with its Instagram, WhatsApp, and Oculus units. 

The policy revision builds on an announcement Facebook made in late March that it will make it simpler for users to examine and change some of the data the network tracks. 

"This is about making the information about how we use people's data and how people can control it more clear," Rob Sherman, deputy chief privacy officer at Facebook, said in an interview. He said Facebook has been working on the proposed policies for months and will seek public comments before implementing them. 

How Facebook articulates its terms of service to its users is important because the company came under fire from the Federal Trade Commission in 2011. The agency said it deceived consumers by telling them they could keep their information private, but then allowed it to be made public. 

A subsequent settlement with the FTC required the company to give consumers notice before sharing information beyond their data settings. The FTC is now investigating Facebook over how Cambridge Analytica used Facebook data. 

Facebook's Sherman said protecting people's privacy is critically important to the company, but didn't comment further on Facebook's interactions with the FTC.

"One of the ideas underlying the FTC consent decree is that we should be clear with people about how we use their information and give them meaningful choices around that," Sherman said. "And that is what we are trying to do with this update."