Facebook CEO Mark Zuckerberg faces senior European Union lawmakers later Tuesday to answer questions about a scandal over the alleged misuse of the data of millions of Facebook users.

In testimony to be broadcast live, Zuckerberg will be questioned by leaders of the European Parliament's main party groups and committees.

Zuckerberg testified last month to the U.S. Congress, but had been noncommittal about appearing in Europe. He sent a senior official to speak to the British parliament and offered to do the same in Brussels, but the EU assembly insisted on hearing him in person.

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Tuesday's hearing was originally supposed to be held behind closed doors. EU Civil Liberties, Justice and Home Affairs Committee President Claude Moraes said the fact that it will now be made public "is very significant."

In his Senate hearing last month, Zuckerberg recited some talking points, such as acknowledging his company "made mistakes" in the data privacy scandal. Zuckerberg faced a broad range of questions including how Facebook works to how its users' data was compromised by Cambridge Analytica.

Under questioning by U.S. lawmakers, the tech billionaire said Facebook users are in "full control of the majority of their data." Yet he acknowledged that he didn't expect a researcher to sell data on 87 million Facebook members to political consulting firm Cambridge Analytica.

Zuckerberg is expected to adhere to a similar script in the EU, with The New York Times reporting that his prepared remarks indicate he'll apologize and admit to a mistake in failing to take a "broad enough view of our responsibilities."