A trio of US firms have taken advisory roles on offshore drilling contractor Transocean’s $1.4bn (£870m) fine for its role in the 2010 Deepwater Horizon oil disaster.

The Swiss-based company has agreed to pay $1bn (£624m) in civil penalties for violating the Clean Waters Act, as well as $400m (£250m) in criminal penalties for a violation committed by Transocean Deepwater, the Houston-based subsidiary of the company that operated the oil rig.