STRUGGLING to convey command of the worsening Gulf of Mexico oil spill, the Obama administration is distancing itself from BP and dispatching the Attorney-General to meet federal and state prosecutors.
Eric Holder's trip could signal that the environmental calamity might become the subject of a criminal investigation. He has said Justice Department lawyers are examining whether there was any ''malfeasance'' related to the leaking oil well, and investigators have sent letters to BP instructing the company to preserve its relevant records.
An avalanche of class action lawsuits are already descending upon the oil giant in courthouses from Texas to Louisiana, Alabama, Mississippi and Florida.
Estimates of the potential cost vary widely. Including the clean-up, compensation and fines, BP could face a bill of $US12 billion ($A14.2 billion), investment bank UBS has suggested.
Jason Kenney, an analyst at ING Commercial, estimates the cost could rise to $US22 billion if the spill continues until August.
Mark Lanier, a Houston lawyer for one group of plaintiffs, said the litigation would make the Exxon Valdez spill in Alaska look like ''an oil leak in a car''.
''This is going to be, in my estimation, the largest tort we've had in this country,'' he told Texas Lawyer magazine.
BP spokesman Andrew Gowers said on Monday: ''We're co-operating fully with all inquiries, and we're doing everything we need to do and more in terms of preserving records.''
The relationship between the federal government and the oil company has been an awkward collaboration all along. But it reached a turning point when the administration said it no longer wanted to share a podium with BP at the daily briefing in Louisiana.
''We've been increasingly frustrated with BP on matters of transparency,'' said an administration official.
It has emerged that BP said in permit applications for drilling in the Gulf that it was prepared to handle an oil spill that released 250,000 barrels a day.
Bob Deans, a spokesman for environmental group the Natural Resources Defence Council, said: ''They told us they had a plan that could deal with the consequences of a worst-case scenario. They don't.''
BP has challenged widespread scientific claims that vast plumes of oil are spreading underwater in the Gulf. BP chief executive Tony Hayward said it had no evidence of underwater oil clouds.
''The oil is on the surface,'' he said. ''Oil has a specific gravity that's about half that of water. It wants to get to the surface because of the difference in specific gravity.''
Dr Hayward's assertion flies in the face of studies by scientists at universities in Florida, Georgia and Mississippi, who say they have detected huge underwater plumes of oil, including one about 80 kilometres from the destroyed rig.
BP's claim is likely to further anger environmentalists and the White House.Read the full story on The Age