The civil lawsuit was brought against the UK oil firm - as well as other companies involved in the accident, including rig-owner Transocean and cement-provider Halliburton - by the US Justice of Department and the US states affected by the oil slick.

BBC: BP: Scope of oil disaster internal probe 'had limitations'

Washington (CNN) -- Oil giant BP and contractor Halliburton knew of potential flaws in the cement slurry used to reinforce the oil well below the Deepwater Horizon rig before it exploded in April, according to a letter Thursday from the lead investigator for a federal probe of the Gulf oil disaster.

CNN: STORY HIGHLIGHTS