Expensive spill (Image: Jae C. Hong/AP/PA)

BP HAS been stung for $4.5 billion – the largest criminal fine in US history – and the company could be liable for a further $21 billion in civil damages. The fine handed down by the US Department of Justice last week relate to the 2010 Deepwater Horizon oil rig disaster in the Gulf of Mexico.

Some $2.4 billion of the fine will go to the National Fish and Wildlife Foundation, which will spend the money on conservation projects in the Gulf region.

The crux of the civil damages case lies in whether BP is shown to have displayed “gross negligence”. Under the Clean Water Act, the company would be liable for a $1100 fine for every barrel of oil leaked into the environment, going up to $4300 per barrel in the case of gross negligence. BP leaked 4.9 million barrels into the Gulf over three months, so could be facing a $21 billion fine.

The company said it would “vigorously defend itself” against the civil claims. The civil trial is due to begin early next year.