Facebook's CEO Mark Zuckerberg answers questions about the improper use of millions of users' data by a political consultancy, at the European Parliament in Brussels, Belgium, in this still image taken from Reuters TV May 22, 2018

Facebook CEO Mark Zuckerberg has been asked to speak before a U.K. parliamentary committee again, and this time Canadian lawmakers are joining in on the request.

British Member of Parliament Damian Collins and Canadian MP Bob Zimmer sent Zuckerberg a joint letter Wednesday requesting Zuckerberg's appearance, according to a tweet from Collins. The letter, and first-time inclusion of Canada, suggests Facebook's challenges are far from over — and potentially broadening.

@DamianCollins: Together with @bobzimmermp, I have today written to Mark Zuckerberg inviting him to give evidence to an international committee to be held in London on 27th November

Zuckerberg addressed U.S. Congress and a committee of the European Union in the months following the Cambridge Analytica data scandal and widespread reports of misuse of Facebook's platform. He's been invited by U.K. lawmakers before, but has yet to appear. Zuckerberg sent Facebook's chief technology officer Mike Schroepfer to speak to Parliament instead.

"The hearing of your evidence is now overdue, and urgent," Collins and Zimmer wrote in the letter. The proposed hearing would take place on Nov. 27, the letter says.

Facebook did not immediately return a request for comment on whether Zuckerberg would attend.

The letter comes just a day after Facebook reported its third-quarter earnings and another decline in European users.