Cambridge Analytica latest: Facebook share price falls sharply as head of security denies he is leaving company

Facebook’s shares have fallen sharply as the company’s head of security was forced to deny he is set to quit over how it handles fake news.

Some $37bn was wiped off the social network’s value on Monday night as it came under fire following allegations that data company Cambridge Analytica (CA) harvested personal details from more than 50 million of its users.

Further claims about CA included allegations the company offered to entrap politicians and used ex-spies to dig for dirt on potential targets. The company denies the allegations.

After the scandal broke, Facebook's Chief Security Officer Alex Stamos said on Twitter that while his role at the firm has changed he is still “fully engaged” with his work there.

Reports suggested he was about to leave the firm due to an “internal dispute” over how to handle 'disinformation'.

He had previously tweeted: "There are a lot of big problems that the big tech companies need to be better at fixing.

"We have collectively been too optimistic about what we build and our impact on the world. Believe it or not, a lot of the people at these companies, from the interns to the CEOs, agree."

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 CA, told Channel 4 News a so-called data grab had been carried out on more than 50 million profiles in 2014.

The UK data protection body is seeking a warrant to search CA’s offices.

Information Commissioner Elizabeth Denham criticised the firm for being "uncooperative" with her probe as she confirmed the Information Commissioner's Office (ICO) would apply for a warrant.

Prime Minister Theresa 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."

It is understood Facebook founder Mark Zuckerberg could be hauled in front of MPs to explain his company's part in the scandal.

CA's chief executive Alexander Nix has claimed his firm 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 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 him 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."

He 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".

A Cambridge Analytica spokesman said: “We entirely refute any allegation that Cambridge Analytica or any of its affiliates use entrapment, bribes, or so-called “honey-traps” for any purpose whatsoever.”

“Cambridge Analytica does not use untrue material for any purpose.”