Facebook faced another round of criticism and tough questions on election meddling Tuesday at a U.K. Parliament hearing with leaders from nine countries—and chief executive officer Mark Zuckerberg’s chair was left empty.

Representatives from the U.K., Canada, Brazil, Latvia, Argentina, Ireland, Singapore, France and Belgium—which in total have more than 400 million constituents—grilled Facebook vice president of policy solutions Richard Allan on fake news, election interference and Zuckerberg’s refusal to appear.