BP is accused of hindering probe into Gulf disaster

The new complaint, by Transocean, follows similar complaints by US politicians about difficulties obtaining necessary information from BP in their investigations.

In a sternly worded letter to BP's lawyers, Transocean said the oil giant has in its sole possession information key to identifying the cause "of the tragic loss of eleven lives and the pollution in the Gulf of Mexico".

BP's refusal to turn over the documents has hampered Transocean's investigation and hindered what it has been able to tell families of the dead and state and federal investigators about the accident, the letter states.

BP and Transocean appear likely to face off in court over how much each should pay out for the tragedy. Transocean owned the Deepwater Horizon, the rig that exploded and sank, killing 11 workers and unleashing millions of gallons of oil. BP was the operator and majority owner of the well.

BP spokeswoman Elizabeth Ashford said Transocean's accusations were misleading and misguided. "We have been at the forefront of co-operating with various investigations commissioned by the US government and others into the causes of the Deepwater Horizon tragedy," she said.

In a biting response, BP told Transocean in a letter that Transocean's claims were "nothing more than a publicity stunt evidently designed to draw attention away from Transocean's potential role in the Deepwater Horizon tragedy."

The row emerged after a new scientific study provided the first conclusive evidence of an underwater plume from the BP spill, and researchers said it could take months for the oil to break down.

Researchers from the Woods Hole Oceanographic Institute, found a plume of oil-based chemicals which measured up to 200m in height and was 2km wide. Transocean said that BP released limited records only after the company agreed to sign a confidentiality agreement at BP's request.

The Senate Energy and Natural Resources Committee had a "stare down" with BP over some of the data it was seeking, said Bill Wicker, a spokesman for committee chairman Jeff Bingaman, a Democrat.

BP requested that congressional staffers sign a nondisclosure agreement. The committee refused, telling the company that it would send all BP's information back. Since then, BP has been forthcoming with data, Mr Wicker said.

Rep Edward Markey, a Democrat and chair of the House's energy and environment subcommittee, said his staff has also had difficulty "prying information" out of BP.

BP's outgoing chief executive, Tony Hayward, personally assured the presidential commission of full co-operation, said David Cohen, a spokesman for the commission.

The panel recently received new information from the company and is now reviewing whether it matches what they asked for.

President Barack Obama warned months ago that companies involved in the accident needed to work together and with the government on the investigation, saying: "I will not tolerate more finger-pointing or irresponsibility."

Transocean wants 16 pieces of technical information from BP, including pressure tests, logs and other data.

TIMELINE

April 20, 2010 - Explosion and fire on Transocean Ltd's drilling rig Deepwater Horizon licensed to BP; 11 workers are killed.

April 22 - The Deepwater Horizon rig, valued at more than $560 million, sinks and a 5-mile oil slick forms.

April 25 - The well's blowout preventer fails.

April 29 - President Barack Obama pledges "every single available resource," including the US military, to contain the spreading spill and says BP is responsible for the cleanup.

May 7 - An attempt to place a containment dome over the spewing well fails.

May 11/12 - Executives from BP, Transocean and Halliburton appear at congressional hearings in Washington.

May 19 - The first heavy oil from the spill hits fragile

Louisiana marshlands.

May 29 - BP says the complex "top kill" process, started three days earlier to plug the well, has failed.

June 1 - U.S. Attorney General Eric Holder says the Justice Department has launched a criminal and civil investigation.

June 18 - Anadarko Petroleum, part owner of the gushing well, says BP's behavior before the blowout was "reckless" and likely represented "gross negligence or willful misconduct."

Aug 19 - BP says it won't put final plug in until September