State officials are angry that federal regulators gave the company permission to try out new chemical techniques to break up and hold back the growing tide of oil.
Despite registering concerns about the potential implications for the environment, marine life and human health, Governor Bobby Jindal's administration was cut out of deliberations over the use of dispersants that break up the oil, as the Environmental Protection Agency granted BP permission to release large quantities underwater.
"We don't have any data or evidence behind the use of these chemicals in the water. We're now basically using one of the richest ecosysystems in the world as a laboratory," complained Alan Levine, the head of Louisiana's Department of Health and Hospitals.
Tony Hayward, BP's chief executive officer, told WAFB Channel 9 news station that the chemical has undergone "lots of testing" and is biodegradable. "We believe it's a very effective way of containing this spill until such time as we can eliminate the leak," he added.
But Robert Barham, the state's Secretary of the Department of Wildlife and Fisheries, stated that it has not been used at such depths before - BP's leak stems from a pipe one mile below the surface - and that its potential impact and consequences are unknown. This includes how it travels through the water over time.
"We're very disappointed in their approach," he said of BP and the EPA. "The federal procedures call for a consensus between federal authorities, the responsible party and the states involved. When we met and expressed our concerns, apparently they decided to go without us."
Efforts to minimise the flow of oil from the ruptured well are continuing today. Technicians stationed on ships anchored above the leaking pipeline - which was sheared off when the Deepwater Horizon drilling rig exploded and sank on April 20 - have been attempting to insert a second, smaller pipe into the break to divert the flow to tankers on the surface. Over the coming days, they also plan to perform a "junk shot", a procedure in which debris including shredded tyres and broken golf balls will be fired into the well at high pressure to create a plug.
The oil industry is facing a growing backlash over the crisis, with President Barack Obama publicly criticising executives on Friday for creating a "ridiculous spectacle" at congressional hearings into the incident. Officials from BP, which leased the rig, Transocean, which owned it, and Halliburton, which was assisting operations to complete the well when tragedy struck, were guilty of "falling over each other to point the finger of blame at somebody else", he said.
Decrying the "cosy relationship" between the oil industry and the federal body that regulates it, the Minerals Management Service, he vowed changes to a regime under which drilling permits were "too often issued based on little more than assurances of safety from the oil companies."
Environmentalists accused the president of acknowledging his administration's errors too late, accusing the Department of the Interior of having turned the Gulf of Mexico into a "sacrifice area" where Big Oil's profits won priority over marine protection laws.
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More than 100 seismic surveys and 300 drilling permits have been issued under Interior Secretary Ken Salazar's watch without the prior environmental consideration that is required under the Marine Mammal Protection Act and the Endangered Species Act, according to the Centre for Biological Diversity. The legislation protects marine life such as whales and dolphins by making it inherent on oil companies to prove that they have taken measures to minimise the environmental impact of drilling and other activities.
"The Department of the Interior is well aware of its obligations under the law," said Miyoko, the Centre's ocean's director, "as well of the harm to endangered whales that can occur from oil industry operations, yet it has simply decided it cannot be bothered. You or I have to follow the law, but Interior Secretary Salazar seems to think that he and the oil companies he is supposedly overseeing do not."
Mr Sakashita added: "Under Salazar's watch, the Department of the Interior has treated the Gulf of mexico as a sacrifice area where laws are ignored and wildlife protection takes a back seat to oil company profits."
Mr Salazar will appear before a hearing on Capitol Hill on Tuesday, to face his first grilling since the crisis began.
The House Committee on Oversight and Government reform has also announced that it is opening an investigation into potential oversight lapses at the Minerals Management Service.
Meanwhile questions remained as to how much oil is really spilling into the sea, with a number of scientists and expert analysts stating that the official figure of approximately 5,000 barrels a day (210,000 gallons) is a gross underestimate. Some believe that it could be 10 times that figure, though none have been granted access to the site to take official readings and there has been scepticism over BP's claims not to know.
John Amos of Skytruth, an environmental monitoring group, said: "There are instruments and technologies available to measure this kind of flow on the sea floor."
He added: "On satellite imagery day in and day out we continue to see an oil slick that's several thousand square miles in size out there and the good news is that it hasn't made serious landfall yet. That may be partly down to the response but also down to wind and current conditions. There's an element of luck in there. But I'm not sure how much longer we can get lucky."