The chairman of the parliamentary inquiry into fake news has threatened Facebook founder Mark Zuckerberg with a formal summons to give evidence before the inquiry in person.
The move came after an "unsatisfactory" hearing with another Facebook executive on Thursday.
In a statement following nearly five hours of testimony from Facebook's chief technical officer Mike Schroepfer, chairman Damian Collins said Mr Schroepfer "failed to answer many specific and detailed questions" about the company's role in a number of ongoing scandals about how political campaigns use the platform to influence voters.
"As an American citizen living in California, Mr Zuckerberg does not normally come under the jurisdiction of the UK Parliament, but he will the next time he enters the country.
"We hope that he will respond positively to our request, but if not the committee will resolve to issue a formal summons for him to appear when he is next in the UK," Mr Collins said.
The statement issued by the select committee for Digital, Culture, Media and Sport accused Mr Schroepfer of failing to answer "nearly 40 separate points", about how Facebook handles users' data and interacts with political campaign groups.
Earlier, Mr Schroepfer told the committee that Aggregate IQ, a Canadian firm employed by multiple Brexit campaign groups, spent two million dollars (£1.4 million) on political adverts on Facebook targeting the EU referendum, but had used "email lists" to target voters rather than Facebook data.
Mr Collins has asked Mr Zuckerberg to give evidence before the committee on multiple occasions since the fake news inquiry formed in late 2017.
In his statement issued after the hearing, Mr Collins said: "We are mindful that it took a global reputational crisis and three months for the company to follow up on questions we put to them in Washington D.C. on February 8.
"We believe that, given the large number of outstanding questions for Facebook to answer, Mark Zuckerberg should still appear in front of the Committee.
"We note, in particular, reports that he intends to travel to Europe in May to give evidence to the European Parliament, and will request that he appears in front of the DCMS Committee before May 24."
If a formal summons is issued and Mr Zuckerberg refuses he could technically be in contempt of Parliament.
However, according to a green paper on parliamentary privilege, "the House's power to punish non-Members for contempt is untested in recent times" .
Facebook is making numerous changes to its platform to emphasise "safety, transparency and control" for users and user data, said Mr Schroepfer, including a "searchable archive" of political advertising in time for the UK local elections in May 2019.
"We feel a deep responsibility to solve these problems and make sure our platform is safe," he said.