"Given your self-declared objective to 'fix' Facebook, and to prevent the platform's malign use in world affairs and democratic process, we would like to give you the chance to appear at this hearing," Damian Collins, chairman of Great Britain's Commons Digital Culture Committee, and Bob Zimmer, chairman of the Canadian parliament's Committee on Access to Information, Privacy and Ethics, wrote in a letter to Facebook.

The two requested in their letter that Zuckerberg appear before their committees in a joint hearing in London on Nov. 27

It's unclear why the two countries are teaming up, but the move is unprecedented. The two parliaments have never before held a joint hearing.

Zuckerberg has already appeared in front of the U.S. Congress and European Parliament but has sent other representatives to speak to members of the British and Canadian parliaments, who have both requested his testimony.