By Donie O’Sullivan and Hadas Gold, CNN Business

LONDON — Facebook faces a potential showdown in London with lawmakers from nine countries as part of an international hearing on disinformation.

Organizers describe the unusual event on Tuesday as the inaugural hearing of the “International Grand Committee on Disinformation.” Topics include data protection and online disinformation.

Lawmakers from Argentina, Belgium, Brazil, Canada, France, Ireland, Latvia, Singapore, and the United Kingdom are attending.

One star witness is missing, however. Facebook CEO Mark Zuckerberg was repeatedly asked to attend, but the tech company has instead dispatched one of his deputies.

Lawmakers will question Richard Allan, the company’s vice president of public policy for Europe, the Middle East and Africa. Allen is a former member of the UK parliament.

The hearing could have major implications for Facebook (FB).

Damian Collins, the lawmaker who leads the British parliamentary committee investigating disinformation, made headlines over the weekend when he obtained internal Facebook documents.

The documents are under court seal in the United States. Facebook wrote to Collins on Sunday asking him to consider hearing from the US court before making the documents public.

Collins wrote in a response to Facebook on Sunday that he had the power to publish the documents.

He said that the documents could shed light on “whether the policies of Facebook … are consistent with the public statements the company has made on the same issues.”

Facebook has endured a year of negative headlines about fake news, election meddling and privacy concerns. Zuckerberg pushed back on some of the unrelenting critical coverage last week in an interview with CNN Business.

Members of parliament have certain legal immunities when conducting official proceedings.

This protection from prosecution ensures freedom of speech, including documents and reports published as part of parliamentary proceedings.