BP is embroiled in a legal battle in Illinois that, against the backdrop of a big spill in Alaska and a fatal explosion in Texas, could enter the debate over whether the UK oil giant has a problem with its US safety culture.

The lawsuit arises from BP's sale for $225m of an Illinois chemicals plant in 2004 to Flint Hills Resources, which is suing the UK company for more than 50 misrepresentations about the plant's environmental compliance, mechanical integrity and production capacities.