The US Justice Department has accused BP of "gross negligence and wilful misconduct" over the Deepwater Horizon disaster, claims which BP deny.

The allegations came in papers filed in the federal court in New Orleans.

The Deepwater Horizon rig had been leased by BP. It exploded on 20 April 2010, killing 11 workers and spilling millions of gallons of crude oil.

If the government can prove gross negligence it can triple the damages BP may have to pay to $21bn (£13bn).

The case is due to go to trial in New Orleans in January 2013, although talks are underway between BP and the US government to try to settle the claims.

"The behaviour, words, and actions of these BP executives would not be tolerated in a middling size company manufacturing dry goods for sale in a suburban mall," the government said in its 39-page filing.