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.

The $400m criminal penalties comprise a $100m (£624m) fine and two separate payments of $150m (£94m) to the US National Academy of Sciences and National Fish and Wildlife Foundation.

California law firm Munger Tolles & Olson provided lead counsel to Transocean, reports The Am Law Daily, with Los Angeles litigation partner Brad Brian heading the team.

Additional counsel was provided by Atlanta-headquartered firm Sutherland Asbill & Brennan and Washington-based litigation boutique Robbins Russell Englert Orseck Untereiner & Sauber. The firms were not immediately available for comment.

The US Department of Justice, which brought the case against Transocean, said the criminal and civil fine imposed on the company was the largest-ever for a violation of the Clean Waters Act, passing the $70m (£44m) penalty handed down last year to MOEX Offshore 2007, a partner with BP in the Gulf well that discharged oil.

Transocean said it had accrued an estimated loss contingency of $1.5bn (£936m) associated with claims made by the end of September last year.

In a statement, the company added: "These important agreements, which the company believes to be in the best interest of its shareholders and employees, remove much of the uncertainty associated with the accident."

"This resolution of criminal allegations and civil claims against Transocean brings us one significant step closer to justice for the human, environmental and economic devastation wrought by the Deepwater Horizon disaster," said US Attorney General Eric Holder.

"This agreement holds Transocean criminally accountable for its conduct and provides nearly a billion dollars in criminal and civil penalties for the benefit of the Gulf states."

The news comes after Transocean's former senior vice president, general counsel and assistant corporate secretary Nick Deeming resigned from the company in October last year for personal reasons.

Deeming's responsibilities as GC were taken on by vice president, deputy GC and chief compliance officer Michael Munro, and senior associate GC and global dispute resolution head David Schwab.

Former Christie's GC Deeming joined Transocean in February 2011, succeeding Eric Brown as the company's legal chief.

The Deepwater oil disaster dates back to April 2010, when the Deepwater Horizon rig experienced an uncontrolled blowout and related explosions and fire, which resulted in the deaths of 11 rig workers and the largest oil spill in US history.