Investigators from Britain's data watchdog have searched the London offices of Cambridge Analytica, the data analytics firm at the centre of a storm over allegations it improperly harvested Facebook data to target US voters.
Around 20 officials, wearing black jackets with "ICOEnforcement" on them, arrived at the firm's central London offices soon after a High Court judge granted a search warrant sought by the Information Commissioner's Office (ICO).
The officials, who were let into the building by security guards, could be seen checking books and papers through the windows of the second-floor offices on London’s busy New Oxford Street.
Elizabeth Denham, head of the ICO, sought the warrant after a whistleblower said Cambridge Analytica had gathered private information of 50 million Facebook users to support Donald Trump's 2016 US presidential campaign.
Britain is investigating whether Facebook, the world's largest social media network, did enough to protect data.
Facebook Chief Executive Mark Zuckerberg has been asked to come before US Congress to explain to explain how the data got into Cambridge Analytica's hands, adding to pressure on the firm, which is under fire from investors and advertisers.
Separately on Friday, Britain's Guardian newspaper said a former Cambridge Analytica political consultant had accused the company's management of misleading the British public about work it did for a pro-Brexit group before the vote to leave the European Union.
Brittany Kaiser, a business development director at the company from 2014 until earlier this year, told the Guardian that Cambridge Analytica carried out data-crunching and analysis work for Leave.EU, while publicly denying it was doing so.
Both Cambridge Analytica and Facebook deny any wrongdoing.
The data watchdog's investigation includes the acquisition and use of Facebook data by Cambridge Analytica, its parent company SCL and academic Dr Aleksandr Kogan, who developed the app used to gather data.
Cambridge Analytica's chief executive Alexander Nix has been suspended while Facebook founder Mark Zuckerberg has been called on to give evidence to MPs.
Efforts by the ICO to investigate Cambridge Analytica had hit a snag on Thursday after a judge adjourned its application to search the British consultancy group's office by 24 hours.
US and European officials have demanded an explanation of how the British consulting firm gained access to the data in 2014 and why Facebook failed to inform its users, raising broader industry questions about consumer privacy.
Mr Zuckerberg said on Wednesday that his company made mistakes in mishandling data and promised tougher steps to restrict developers access to data.
