BBC: Cambridge Analytica The Story so far

It's a sensational story containing allegations of sleaze, psychological manipulation and data misuse that has provoked an internationally furious response.

Tech giant Facebook and data analytics firm Cambridge Analytica are at the centre of a dispute over the harvesting and use of personal data - and whether it was used to influence the outcome of the US 2016 presidential election or the UK Brexit referendum.

Both firms deny any wrongdoing.

How has Cambridge Analytica been accused of sleazy tactics?

Channel 4 News sent an undercover reporter to meet executives from data analytics firm Cambridge Analytica.

The firm had been credited with helping Donald Trump to presidential victory.

The reporter posed as a Sri Lankan businessman wanting to influence a local election.

Cambridge Analytica boss Alexander Nix was apparently filmed giving examples of how his firm could discredit political rivals by arranging various smear campaigns, including setting up encounters with prostitutes and staging situations in which apparent bribery could be caught on camera.

The firm denies all the claims and says the documentary was "edited and scripted to grossly represent the nature of those conversations". It claims the conversations were led by the reporters.

"I must emphatically state that Cambridge Analytica does not condone or engage in entrapment, bribes or so-called 'honeytraps', and nor does it use untrue material for any purpose," said Mr Nix.

What was Facebook's role?

In 2014 a quiz on Facebook invited users to find out their personality type.

It was developed by University of Cambridge academic Aleksandr Kogan (the university has no connections with Cambridge Analytica).

As was common with apps...