Facebook and the analytics company that worked with Donald Trump’s election team have come under mounting pressure, with calls for investigations and hearings to explain a vast data breach that affected tens of millions of people.

In Britain, the head of the parliamentary committee investigating fake news accused Cambridge Analytica and Facebook of misleading MPs after revelations in the Observer that more than 50m Facebook profiles were harvested and used to build a system that may have influenced voters in the 2016 presidential campaign.

The Conservative MP Damian Collins said he would call the heads of both companies, Alexander Nix and Mark Zuckerberg, to give further testimony.

His intervention came after a whistleblower spoke to the Observer and described how the profiles, mostly of US voters, were harvested for Cambridge Analytica, in one of Facebook’s biggest ever data breaches.

The disclosures caused outrage on both sides of the Atlantic; in the US, a state attorney general has called for investigations and greater accountability and regulation.

There have been reports that Cambridge Analytica is trying to stop the broadcast of a Channel 4 News exposé in which Nix is said to talk unguardedly about the company’s practices. According to the Financial Times, reporters posed as prospective clients and secretly filmed a series of meetings, including one with the chief executive. The report is due to air this week.

Collins, the chair of the Commons digital, culture, media and sport select committee, said he would be recalling Nix to give further testimony to explain why he had told MPs last month that his company had not received data from Facebook.

“We will be contacting Alexander Nix next week asking him to explain his comments,” he said.

Collins will also call on Zuckerberg to testify. He said the company appeared to have previously sent executives who were able to avoid difficult questions and who “claimed not to know the answers”.

The two men may also face a summons from US lawmakers. Adam Schiff, the top Democrat on the House intelligence committee, called for Cambridge Analytica to be “thoroughly investigated” and said Facebook must answer questions about how it came to provide private user information to an academic with links to Russia.

The Republican majority on the House intelligence committee announced this week they were winding up their investigation into Russia’s election interference, concluding there was no collusion with Trump’s campaign and, even more controversially, that Moscow did not seek to assist him. Schiff fiercely condemned that decision and said the Democratic minority would continue working on prescriptions for protecting the country in the future.

“This raises serious questions about the level of detail that Cambridge Analytica knew about users, whether it acquired that information illegally and whether it sought to abuse that information in support of President Trump’s political campaign in the United States or Brexit in the United Kingdom,” he told the Guardian.

“The company has repeatedly touted its ability to influence voters through ‘psychographic’ targeting and has claimed it was the fundamental reason that Donald Trump won the 2016 election. Indeed, it may be that through Cambridge Analytica, the Trump campaign made use of illegitimately acquired data on millions of Americans in order to help sway the election.”

Trump’s campaign hired Cambridge Analytica in June 2016 and paid it more than $6.2m, according to Federal Election Commission records. It denies using any Facebook data in the campaign.

Shortly before the story broke, Facebook’s external lawyers warned the Observer that it was making “false and defamatory” allegations and reserved Facebook’s legal position. Facebook denies that the harvesting of tens of millions of profiles by Cambridge Analytica, working with Cambridge academic Aleksandr Kogan and his company Global Science Research (GSR), was a data breach.

It also suspended the whistleblower Chris Wylie from the platform “pending further information” over misuse of data, along with his former employer Cambridge Analytica and its affiliates, and the academic they worked with, Kogan.

The public attack on Wylie came after he had approached the tech company about the data breach, offering to help investigate. He described it as a chilling attack on someone acting in the public interest.

“They acknowledged my offer but then turned around and shot the messenger. I’m trying to make amends for my mistakes and so should Facebook,” he told the Guardian. “Facebook has known about this for at least two years and did almost nothing to fix it. This is not new. And it’s only by coming forward that Facebook is now taking action. People need to know this kind of profiling is happening.”

Collins said his committee wanted more information from Facebook about the circumstances around the breach. “Data has been taken from Facebook users without their consent, and was then processed by a third party and used to support their campaigns. Facebook knew about this, and the involvement of Cambridge Analytica with it.”

“We need to hear from people who can speak about Facebook from a position of authority that requires them to know the truth,” Collins said. “Someone has to take responsibility for this. It’s time for Mark Zuckerberg to stop hiding behind his Facebook page.”

Last month, both Facebook representatives and Nix told the parliamentary inquiry into fake news that the company did not have or use private Facebook data, or any data from GSR.

But in its statement on Friday night, explaining why it had suspended Cambridge Analytica and Wylie, Facebook said it had known in 2015 that profiles were passed to Nix’s company.

“In 2015, we learned that a psychology professor at the University of Cambridge named Dr Aleksandr Kogan lied to us and violated our ‘platform policies’ by passing data from an app that was using Facebook Login to SCL/Cambridge Analytica,” the statement said.

Collins attacked Facebook for appearing to have been “deliberately avoiding answering straight questions” in testimony to the committee.

“It is now clear that data has been taken from Facebook users without their consent, and was then processed by a third party and used to support their campaigns,” Collins said. “Facebook knew about this, and the involvement of Cambridge Analytica with it.”

Cambridge Analytica responded to the Observer story on Twitter before Collins had said Nix would be recalled. “We refute(s) these mischaracterizations and false allegations,” it said.

“Reality Check: Cambridge Analytica uses client and commercially and publicly available data; we don’t use or hold any Facebook data,” the company said. “When we learned GSR sold us Facebook data that it shouldn’t have done, we deleted it all – system wide audit to verify.”