Facebook is being sued by a top prosecutor in Washington DC over the Cambridge Analytica scandal.

District of Columbia attorney general Karl Racine announced the lawsuit today, saying he's taking the action against the social media company for failing to protect user data.

Earlier this year, Facebook revealed that 87 million people around the world may have had their data improperly shared with the UK-based political consultancy firm Cambridge Analytica.

The company accused an academic of violating its terms by passing on data from a personality test app - thisisyourdigitallife - to the consultancy firm.

The vast majority of accounts affected - more than three-quarters - are believed to belong to people in the US.

Mr Racine claims the scandal allowed the user data of around 340,000 residents in his district to be acquired for 'political purposes'.

In a statement, he said: “Facebook failed to protect the privacy of its users and deceived them about who had access to their data and how it was used.

“Facebook put users at risk of manipulation by allowing companies like Cambridge Analytica and other third-party applications to collect personal data without users’ permission. Today’s lawsuit is about making Facebook live up to its promise to protect its users’ privacy.”

His office is now seeking an injunction "to ensure Facebook puts in place protocols and safeguards to monitor users’ data and to make it easier for users to control their privacy settings", as well as restitution for consumers, penalties and costs.

The scandal has previously prompted investigations in several jurisdictions, while Cambridge Analytica itself - which disputed some of Facebook's claims - has since ceased operations.

Facebook boss Mark Zuckerberg has apologised for the situation, saying: "It’s clear now that we didn’t do enough."

It was one of a number of high-profile controversies to hit the social media giant in recent months, mostly revolving around the company's data practices. 

Only yesterday, an investigation in the New York Times claimed that the company gave other tech giants such as Microsoft, Spotify and Netflix "far greater access to people’s data than it has disclosed".