AS Facebook CEO Mark Zuckerberg hides behind closed doors to prepare for a two-day showdown on Capitol Hill, more than 311,000 Australian Facebook users are set to find out if their privacy has been breached.

The embattled social media network is expected from Monday afternoon to notify the 87 million users worldwide whose data may have been unknowingly and “improperly” shared with British political consulting agency, Cambridge Analytica.

About one in 50 Australian users and one in every three American users are among those affected.

Cambridge Analytica developed controversial tools for use in political campaigns and worked on Donald Trump’s run for US president.

It says it received data on 30 million users but never used that information in the 2016 campaign.

The social media giant will also show each of its 2.2 billion users a message prompting them to review the apps and websites connected to their account.

On Facebook’s newsroom updates, it gave users a preview look at what they are expected to see.

It stated: “Finally, starting on Monday, April 9, we’ll show people a link at the top of their News Feed so they can see what apps they use — and the information they have shared with those apps. People will also be able to remove apps that they no longer want. As part of this process we will also tell people if their information may have been improperly shared with Cambridge Analytica.”

The Privacy Commissioner is investigating whether Facebook breached the Privacy Act, which requires organisations meet certain obligations including taking reasonable steps to ensure personal information is held securely. Facebook has lost $100 billion of its sharemarket value since the Cambridge Analytica scandal broke three weeks ago.

It last week suspended another political consulting firm amid media reports it had ties to Cambridge Analytica and received more than $4.5 million during Brexit from the triumphant Vote Leave campaign The Canadian-based AggregateIQ says it has never been part of Cambridge Analytica or parent company SCL and has never entered into a contract with Cambridge Analytica.

As users eagerly await to hear of any potential breach, Zuckerberg, 33, is behind closed doors with a high-level team of experts who are helping him prepare his testimony before the US Senate Commerce and Judiciary committees.

According to the New York Times, Facebook has reportedly hired Reginald J. Brown, a former special assistant to President George W. Bush, a team from the law firm WilmerHale and other consultants to coach Zuckerberg.

According to the New York Times, sources close to the preparations said he was being coached on different questions he may get asked, how to answer them, and how to pace his answers and react if he gets interrupted. A spokesman for Facebook declined to comment on the report.

After his first day of testimony, Zuckerberg will appear before the House Energy and Commerce Committee.

Experts have revealed what they expect the hearings to be like for the Facebook creator — and it’s not positive.

“He’s going to take a hell of a beating,” David Fuscus, president and CEO of Xenophon Strategies, a crisis communications firm that has coached dozens of executives to testify on Capitol Hill, told CBC.

“And if he doesn’t want to just be a punching bag, he’s got to find a way to get his messages through.”

Rachel Bovard, director of policy at the Conservative Partnership Institute and a longtime Senate staffer described it as a “trap”, to CBC.

“Part of the public catharsis is being Congress’s whipping boy in a very public way,” she said.

In these hearings, politicians have signalled they intend to get tough on Facebook and other online services over privacy. They are also expected to grill Zuckerberg on how user privacy was abused, his leadership, and how Facebook plans to ensure it doesn’t occur again.

“A day of reckoning is coming for websites like @facebook,” Democratic Senator Ed Markey wrote on Twitter.

“We need a privacy bill of rights that all Americans can rely upon.” Representative Ro Khanna, a California Democrat, agreed that legislation is needed “to protect Americans’ dignity and privacy from bad faith actors like Cambridge Analytica, who use social media data to manipulate people.” Khanna tweeted that “self-regulation will not work. Congress must act in the public interest to protect consumers and citizens.”

Several politicians and activists believe the United States should follow the lead of Europe’s data protection law set to be implemented in May, which has strict terms for notification and sharing of personal data online.
Sheryl Sandberg, Chief Operating Officer (COO) of Facebook.

The hearings come as separately, Facebook chief operating officer Sheryl Sandberg backed out of an interview with US ABC anchor George Stephanopoulos.

In recent days, she has offered her fresh apologies to users for failing to do enough on privacy and data protection.

“We know that we did not do enough to protect people’s data,” Sandberg told National Public Radio. “I’m really sorry for that. Mark is really sorry for that, and what we’re doing now is taking really firm action.” Sandberg said Facebook first became aware in 2015 that Cambridge Analytica had obtained user data from a researcher who put up a poll on the social network.

“When we received word that this researcher gave the data to Cambridge Analytica, they assured us it was deleted,” she said.

“We did not follow up and confirm, and that’s on us — and particularly once they were active in the election, we should have done that.”