WASHINGTON/VENICE, Louisiana (Reuters) - President Barack Obama on Saturday blamed the massive Gulf of Mexico oil spill on "a breakdown of responsibility" at energy giant BP Plc as he unveiled a commission to investigate the disaster.
Obama, in his weekly radio and Internet address, also said offshore oil drilling could only go forward if there were assurances that such accidents would not happen again.
While ramping up pressure on companies linked to the still uncapped spill -- BP, Halliburton and Transocean Ltd -- he said he would also hold Washington accountable for mending its ways.
"First and foremost, what led to this disaster was a breakdown of responsibility on the part of BP and perhaps others, including Transocean and Halliburton," Obama said in his toughest remarks yet on companies linked to the spill.
"And we will continue to hold the relevant companies accountable not only for being forthcoming and transparent about the facts surrounding the leak, but for shutting it down, repairing the damage it does, and repaying Americans who've suffered a financial loss," he said.
A month after the well blowout and rig explosion that killed 11 workers, sheets of rust-colored heavy oil are clogging fragile marshlands on the fringes of the Mississippi Delta, damaging fishing grounds and wildlife.
In his executive order announcing former Democratic Senator Bob Graham and former Environmental Protection Agency chief William Reilly would co-chair the commission, Obama made his first reference to the possibility of a criminal probe.
"The commission shall ensure that it does not interfere with or disrupt any ongoing or anticipated civil or criminal investigation or law enforcement activities or any effort to recover response costs or damages arising out of the Deepwater Horizon explosion, fire and oil spill," the order stated.
The administration is keeping the pressure on BP on many fronts as it strives to show it is being resolute in the face of what many believe is already the worst U.S. oil spill, eclipsing the 1989 Exxon Valdez accident in Alaska.
The U.S. Environmental Protection Agency expressed frustration on Saturday when it released BP's response to its directive on dispersants instructing the company to evaluate pre-approved dispersants for toxicity and effectiveness.
It accused BP and some of the manufacturers involved of withholding information by invoking business confidentiality.
"EPA continues to strongly urge these companies to voluntarily make this information public so Americans can get a full picture of the potential environmental impact of these alternative dispersants," it said. It did not name the companies.
In its response released by the EPA, BP said Corexit, a dispersant manufactured by Nalco Holding Co that it has been using, was the only one immediately available in sufficient quantities to tackle the spill and "remains the best option for subsea application."
It also said that "within 28 days of application it does not persist in the environment" and asked to discuss the situation with the Coast Guard and the EPA before they issue "directives requiring a change in dispersant products."
Some environmentalists worry the chemicals in dispersants may have a lasting harmful impact.
EPA Administrator Lisa Jackson will return to the Gulf Coast on Sunday to monitor its response while Secretary of the Interior Ken Salazar travels to the BP Command Center in Houston to get an update from the federal science team working on the problem.
BP made no immediate comment on Obama's suggestion that it was to blame for the deep-sea disaster. But the company's chief executive, Tony Hayward, said he welcomed the establishment of the commission and pledged to work with its co-chairmen.
"We share the goal of the president and the public to know what happened to cause this accident and what regulatory and industry changes are needed to help prevent something like this from happening again," Hayward said in a statement.
BP on Friday revised downward an earlier estimate that one of its containment solutions, a 1-mile-long siphon tube inserted into the larger of two seabed leaks, was catching 5,000 barrels (210,000 gallons/795,000 liters) of oil per day.
BP captured 2,200 barrels in the 24 hours to midnight, according to the incident response team, the same figure it had for the previous 24-hour period.
"To me from the very beginning with BP it was nothing but public relations," said Roger Halphen, a south Louisiana school teacher who has worked both in the oil industry and as a commercial fisherman.
"It's just a disaster. Everybody was sleeping on this and all of a sudden here it is," he said of oil fouling the coast.
The weather at least was cooperating.
"There's very little chance of rain and plenty of visibility with low winds and fairly smooth seas," said Ken Graham, head of the National Weather Service office in New Orleans. "For things they need to do out there, they've got a pretty good window of opportunity.
Favorable conditions are expected through the weekend, he said. High winds and rough seas can hinder efforts to burn off or skim oil from the surface.
Louisiana authorities are desperate to start building sand levees to keep the spill from swamping their coast, but experts have serious doubts about the $350 million project.
The company's next planned step is a "top kill" -- pumping heavy fluids and then cement into the gushing well to plug it.
Many scientists dismiss an original 5,000 bpd estimate of the total leaking oil -- often defended by BP executives -- as ridiculously low and say it could be 70,000 barrels (2.9 million gallons/11 million liters) per day or more.
Additional reporting by Anna Driver in Houston and Lisa Richwine in Washington; writing by Ed Stoddard and Tom Brown; editing by Mohammad Zargham