Federal Trade Commission 'investigates Facebook' over Cambridge Analytica

The US Federal Trade Commission is reported to be investigating Facebook after allegations that 50 million users' private information was misused by a political consultancy firm.

Cambridge Analytica, used by Donald Trump in the 2016 US election, has been accused by a whistleblower of taking the personal data unknown to users.

Facebook is due to face the US Congress on Wednesday as pressure grows.

Its stock has continued to slide, following Monday's steep decline.

Both the British Parliament and the European Parliament have also called on Facebook boss Mark Zuckerberg to give evidence to them.

Cambridge Analytica, which is based in London, denies any wrongdoing.

The FTC, an independent agency of the US government, is tasked with protecting American consumers.

• Cambridge Analytica: The story so far

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What are the accusations?

Christopher Wylie, who worked with Cambridge Analytica, alleges that it amassed large amounts of data through a personality quiz on Facebook called This is Your Digital Life.

He says that 270,000 people took the quiz but the data of some 50 million users, mainly in the US, was harvested without their explicit consent via their friend networks.

Mr Wylie says that data was sold to Cambridge Analytica, which then used it to psychologically profile people and deliver pro-Trump material to them, with a view to influencing the outcome of the 2016 election.

Cambridge Analytica insists it followed the correct procedures in obtaining and using data but it was suspended from Facebook last week.