Facebook CEO Mark Zuckerberg has declined a request to discuss fake news and data privacy in front of government officials from the U.K. and Canada, officials from those countries said in a signed letter Wednesday. Three more countries are also joining in the call for Zuckerberg to appear.

Late last month, U.K. and Canadian lawmakers called on Zuckerberg to attend a "special joint parliamentary hearing" in London on Nov. 27 for an "international grand committee' on disinformation and fake news." Now, officials from Argentina, Australia and Ireland have joined the call, according to the latest letter, which said Facebook declined the original invitation on Friday.

Facebook shared with CNBC the letter it sent to UK and Canadian lawmakers on Nov. 2 declining the request, but declined to comment further.

The letter, which is signed by Facebook's heads of public policy in the UK and Canada, acknowledges "the seriousness of the Cambridge Analytica issue" and stands by its choice to send senior representatives of the company to confront lawmakers instead of Zuckerberg. Facebook said in the letter it has already submitted written answers to lawmakers' inquiries and given extensive testimony in the UK Parliament.

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"We are very disappointed by this dismissive response," the signatories wrote. Zuckerberg should give the 170 million collective users in these countries "the same line of accountability" that they gave users in the U.S. and European Union by showing up to confront lawmakers directly, they said, restating their request for the chief executive to attend the hearing.