Update 1.20pm: Facebook founder Mark Zuckerberg has been summoned to give evidence before the parliamentary inquiry into fake news after revelations about users' personal data held by British firm Cambridge Analytica (CA).
Damian Collins, chair of the inquiry, accused the social media giant of giving answers "misleading to the Committee" at a previous hearing which asked whether information had been taken without users' consent
"It is now time to hear from a senior Facebook executive with the sufficient authority to give an accurate account of this catastrophic failure of process," Mr Collins wrote in a letter to Mr Zuckerberg.
"Given your commitment at the start of the New Year to 'fixing' Facebook, I hope that this representative will be you," he added.
Facebook's former VP of ads Andrew “Boz” Bosworthhas added his comments to the furore in a detailed facbook post, in which he said : “This is the opposite of our business model...Our interests are aligned with users when it comes to protecting data.” :
Update 11:30: Cambridge Analytica boss denies using entrapment
The boss of Cambridge Analytica has denied using entrapment following a Channel 4 investigation.
Alexander Nix, chief executive of the firm, told reporters outside its offices in New Oxford Street, London, that "appearances can be deceptive" when asked if the firm had previously used entrapment following the disclosures on Channel 4 News .
When asked if CA would abandon its political work Mr Nix gave no reply but firmly denied he had misled parliament over its use of data, saying "absolutely not".
Mr Nix arrived as the Information Commissioner Elizabeth Denham worked to secure a warrant to search computers and servers to investigate the firm's activities.
Ms Denham criticised CA for being "unco-operative" with her probe as she confirmed the Information Commissioner's Office (ICO) would apply for a warrant to help her examine the firm's activities.
Update 10.30: MPs air concerns over Cambridge Analytica disclosures
Politicians from across the House of Commons have been airing their concerns over the use of Facebook data by the company Cambridge Analytica, which has boasted about using personal information to target voters during elections.
Downing Street released a statement calling the breach "very concerning" on Monday, but further disclosures in a Channel 4 News investigation have shown that the company discussed propaganda, disinformation and extortion tactics with prospective clients.
Liam Byrne, Labour's shadow minister for digital, called the combination of big data companies and foreign powers an "unholy alliance" which demanded legislation to stop any "interfering in our democracy".
Paddy Ashdown suggested making personal data the same as personal property in the eyes of the law, including the right to take a share of any profits.
"Cambridge Analytica & data harvesting: the only protection is to set in law that personal data is part of individual property to which they have full property rights and that this cannot be used without their formal agreement, including the right to share in the profits created," he wrote.
Cambridge Analytica & data harvesting: the only protection is to set in law that personal data is part of individual property to which they have full property rights and that this cannot be used without their formal agreement, including the right to share in the profits created.— Paddy Ashdown (@paddyashdown) March 20, 2018
And Darren Jones, a Labour MP on the science and technology select committee, shared concerns that the forthcoming data protection bill could give a "get-out clause" to companies like Cambridge Analytica.
Liberal Democrat leader Vince Cable took the opportunity to question Cambridge Analytica's possible role in the Brexit vote.
While the leaders of Leave.EU had previously boasted of using Cambridge Analytica's services, they have since said a contract was never signed.
"Now we need to find out if #CambridgeAnalytics [sic] and leak from #Facebook played a key role in #Brexit #Referendum," wrote Mr Cable on Twitter.
And as the hashtag #DeleteFacebook started to circulate online, the SNP's Stewart McDonald admitted he deleted his page a year ago and predicted others would do the same.
"Though I maintain an MP Facebook page for constituents, I'm now glad I deleted my personal Facebook page over a year ago," he wrote.
"Too full of advertising and obscure profiles requesting to be 'friends'. Quite sure many will be doing the same after #CambridgeAnalyticaUncovered."
Though I maintain an MP Facebook page for constituents, I’m now glad I deleted my personal Facebook page over a year ago. Too full of advertising and obscure profiles requesting to be ‘friends’. Quite sure many will be doing the same after #CambridgeAnalyticaUncovered— Stewart McDonald MP (@StewartMcDonald) March 20, 2018
Many MPs praised journalists at Channel 4 News and the Observer for their work in exposing how Cambridge Analytica had both harvested and stored personal data from Facebook users.
"If you care at all about democracy & believe elections should be open & not corrupted please watch this; the story Cambridge Analytica didn't want you to see," wrote Labour's Yvette Cooper, commending journalists for their investigative work.
If you care at all about democracy & believe elections should be open & not corrupted please watch this; the story Cambridge Analytica didn’t want you to see. Powerful Channel4News investigation following @carolecadwalla & @guardian work https://t.co/1lfDjbh52s— Yvette Cooper (@YvetteCooperMP) March 19, 2018
Earlier: Cambridge Analytica accused of using personal data of 50 million Facebook users to influence US election
The UK's data watchdog says it will seek a warrant to look at the databases and servers used by British firm Cambridge Analytica.
The company is accused of using the personal data of 50 million Facebook members to influence the US presidential election in 2016.
The firm denies any wrongdoing.
Information Commissioner Elizabeth Denham criticised CA for being "unco-operative" with her probe as she confirmed the Information Commissioner's Office (ICO) would apply for a warrant to help her examine the firm's activities.
Meanwhile, further claims about CA included allegations the company offered to entrap politicians and used ex-spies to dig for dirt on potential targets.
But the firm's boss Alexander Nix claimed CA was the target of media attacks because of its role in US President Donald Trump's successful election campaign.
An undercover investigation by Channel 4 recorded CA's chief executive Mr Nix suggesting ways he could help a potential client.
A reporter posing as a fixer for a wealthy client hoping to get candidates elected in Sri Lanka met with Mr Nix and other senior figures from CA.
Asked about what "deep digging" could be done, Mr Nix told the reporter: "Oh, we do a lot more than that.
"I mean deep digging is interesting but you know equally effective can be just to go and speak to the incumbents and to offer them a deal that's too good to be true, and make sure that that's video recorded, you know, these sorts of tactics are very effective instantly having video evidence of corruption, putting it on the internet, these sorts of things."
Mr Nix said they could "send some girls around to the candidate's house", adding that Ukrainian girls "are very beautiful, I find that works very well", Channel 4 reported.
Mr Nix told BBC's Newsnight the Channel 4 sting was "intended to embarrass us".
"We see this as a co-ordinated attack by the media that's been going on for very, very many months in order to damage the company that had some involvement with the election of Donald Trump," he said.
Mr Nix said he had a "huge amount of regrets about the fact that we, maybe, undertook this meeting and spoke with a certain amount of hyperbole about some of the things that we do".
He added: "I have some regrets about the way that I have represented what the company does. I certainly feel that the air of mystery and negativity that surrounds the work of Cambridge is misfounded and, as the CEO, I take responsibility for that."
CA was suspended from Facebook last week after it emerged that data on millions of users had not been destroyed as agreed.
Whistleblower Chris Wylie, a former research director at the UK-based company, told Channel 4 News a so-called data grab had been carried out on more than 50 million profiles in 2014.
Damian Collins, chairman of the House of Commons Digital, Culture, Media and Sport Committee, has called on Facebook founder Mark Zuckerberg to appear before MPs to explain his company's actions and Downing Street has also said it has concerns.
Asked about the reports, Mrs May's spokesman said: "It is absolutely right that the Information Commissioner is investigating this matter.
"We expect Facebook, Cambridge Analytica and all the organisations involved to co-operate fully."
The ICO is investigating the use of personal data for political campaign, including the activities of CA.
An investigation by Facebook at CA's London office was halted in order to allow the ICO to pursue its inquiry.
An ICO spokesman said: "On March 7, the Information Commissioner, Elizabeth Denham issued a Demand for Access to records and data in the hands of Cambridge Analytica.
"Cambridge Analytica has not responded to the Commissioner by the deadline provided; therefore, the Information Commissioner is seeking a warrant to obtain information and access to systems and evidence related to her investigation.
"On March 19, Facebook announced that it will stand down its search of Cambridge Analytica premises at the Information Commissioner's request. Such a search would potentially compromise a regulatory investigation. "