So, that's a "No" RSVP from Facebook.

Facebook has declined the UK and Canadian lawmakers' invitation to Mark Zuckerberg to testify before a joint international committee.

In October, UK and Canadian officials banded together to investigate political manipulation online. They invited Mark Zuckerberg to testify, particularly on Cambridge Analytica.

Zuckerberg has already testified before a European Union hearing, and other Facebook officials have been deployed to the UK, which Facebook notes in its letter to the leading MPs behind the commission. Facebook is now saying that — though it will continue to work with lawmakers around the world — those appearances were sufficient.

"As your letter states, it is not possible for Mr. Zuckerberg to be available to all Parliaments," the letter from Facebook reads. "While he is unable to accept your invitation we continue to fully recognize the seriousness of these issues and remain committed to working with you to provide any additional relevant information you require for your respective inquiries."

The UK and Canadian officials reportedly termed the body an "international grand committee." UK MP Damian Collins told the Associated Press that Ireland, Argentina, and Australia had also signed on. But hopes of creating digital United Nations of sorts, to which Facebook was beholden, seem to have stuttered.

"Five parliaments are now calling on you to do the right thing by the 170 million users in the countries they represent,” Collins told the AP.

That's a call that Facebook is apparently not picking up.