The testimony was public, unlike the proposed meeting with the European Parliament.
And according to an European Union parliament source, around half the groups wanted an open hearing with the Committee on Civil Liberties, Justice and Home Affairs - with only a small majority of the Conference of Presidents agreeing to a closed meeting.
"Our citizens deserve a full and detailed explanation", Tajani added.
"I appreciate that Mark Zuckerberg has made a decision to present himself in front of the representatives of 500 million Europeans", he said.
After Schroepfer faced a set of tough questions before on MPs' in place of Zuckerberg last month, Collins threatened to compel the Facebook CEO to appear before the committee, writing to Stimson: "It is worth noting that, while Mr Zuckerberg does not normally come under the jurisdiction of the UK Parliament, he will do so the next time he enters the country". "I welcome Mark Zuckerberg's decision to appear in person before the representatives of 500 million Europeans", Mr Tajani said. "There are more EU users on FB than there are in the US and Europeans deserve to know how their data is handled", Jourova said on Twitter. The committee will use the opportunity to address numerous inconsistencies in his previous evidence.
Zuckerberg will meet leaders behind closed doors, something that's being slammed by Liberal leader Guy Verhofstadt on Twitter.
However, there are some Parliamentary members who are unhappy that the meeting will be behind closed doors.
Facebook admitted earlier this month that up to 87 million users may have had their data hijacked by British consultancy Cambridge Analytica, which worked for US President Donald Trump during his 2016 campaign.
The EU Justice Commissioner also wants a public hearing.
Mr Zuckerberg has ignored repeated calls to speak before the Digital, Culture, Media and Sport Committee as part of its investigation into data protection and fake news in the wake of the Cambridge Analytica data scandal.