Facebook founder and chief executive Mark Zuckerberg is facing intensified calls to appear in person at investigations into the social network's conduct.
His company has been accused of failing to properly inform users that their profile information may have been obtained and kept by Cambridge Analytica, a data firm widely-credited with helping Donald Trump win the 2016 US presidential election.
Facebook said on Friday it had blocked Cambridge Analytica from Facebook while it investigated claims the London-based firm did not, as promised, delete data that was allegedly obtained using methods that were in violation of Facebook's policies.
Both Cambridge Analytica and Facebook deny any wrongdoing.
Despite pledging that in 2018 he would "fix" his company, Facebook founder Mark Zuckerberg has managed to avoid engaging with the site's growing number of critics - instead sending lawyers or policy bosses to various committee hearings.
The 33-year-old's recent remarks on some of Facebook's controversies have been communicated in the relatively safe space of a blog post or video message published on his Facebook page.
Facebook and Trump data firm 'misled' MPs
US to investigate Trump campaign data firm
Tech Tent: Facebook and Google take action
With the building row over how Facebook data may have been used to fuel highly-targeted political propaganda, several influential figures on both side of the Atlantic this weekend said it was time for Mr Zuckerberg to step up to publicly defend - or at least justify - his creation.
Some called for investigations into whether Mr Zuckerberg's company may have violated laws governing disclosure of a data breach - and also rules on properly obtaining a user's consent to collect personal information.
"This is a major breach that must be investigated," demanded Democratic Senator Amy Klobuchar of Minnesota.
"It’s clear these platforms can’t police themselves. I've called for more transparency and accountability for online political ads. They say 'trust us'."
She added: "Mark Zuckerberg needs to testify before Senate Judiciary."
'High on themselves'
That sentiment was backed by Adam Schiff, the highest-ranking Democrat on the House Intelligence Committee, which is already investigating social media manipulation in the run up to the 2016 presidential election.
"I think it would be beneficial to have him come testify before the appropriate oversight committees," he told the Washington Post.
"And not just Mark but the other CEOs of the other major companies that operate in this space."
On Sunday morning TV, Florida senator and former presidential hopeful Marco Rubio told NBC's Meet the Press he felt technology companies acted as if they are "above" regulations.
Eight reasons Facebook has peaked
Social networks 'too slow' on changes
Facebook broke German privacy laws
"Their growth has been a lot faster than perhaps their ability to mature institutionally from within on some of these challenges that they're facing," he said.
"I think another part about it is sometimes these companies grow so fast and get so much good press, they get up high on themselves that they start to think that perhaps they're above sort of the rules that apply to everybody else."
