A Canadian Parliament committee on Tuesday voted unanimously to issue a subpoena calling for appearances from Facebook CEO Mark Zuckerberg and COO Sheryl Sandberg.
The Facebook executives were reportedly invited to appear before the International Grand Committee on Disinformation and "Fake News" in Ottawa, Canada, later this month, but neither responded.
Zuckerberg also ignored requests to address a Canadian committee looking into election meddling and disinformation on Facebook.
The subpoena can reportedly only be enforced if Zuckerberg and Sandberg go to Canada.
"We're hoping this shows them we're serious," said Bob Zimmer, chair of Canada's Standing Committee on Access to Information, Privacy and Ethics.
If Zuckerberg and Sandberg don't respond to the subpoena or refuse to appear before the committee, the committee will "submit to the full Parliament a motion to hold them in contempt," said Zimmer.
Facebook and Zimmer didn't immediately respond to requests for comment.
Last year, Zuckerberg testified before Congress following the Cambridge Analytica scandal, in which data from as many as 87 million Facebook users was improperly shared with the political consultancy.