NEW ORLEANS, Louisiana (AFP) - – BP officials desperately searched Monday for a new way to stop an enormous Gulf of Mexico oil spill after efforts to cap a gushing leak with a containment dome hit a snag.

British energy giant BP, which owns the lion's share of the leaking oil and has accepted responsibility for the clean-up, was facing the possibility that, failing a swift fix with the containment dome, the crisis could spiral into an even worse environmental calamity

The White House also was scrambling to contain fallout from the disaster threatening to take a toll on President Barack Obama's political and energy agenda.

In Washington Obama on Monday would meet with Cabinet members and senior staff "to review BP efforts to stop the oil leak, as well as to decide on next steps to ensure all is being done to contain the spread, mitigate the environmental impact and provide assistance to affected states," a White House statement said.

The Minerals Management Service also said it "continues to work with BP to explore all options that could stop or mitigate oil leaks from the damaged well."

The BP-leased Deepwater Horizon rig sank some 80 km (50 miles) southeast of Venice, Louisiana, on April 22, two days after an explosion that killed 11 workers.

The riser pipe that had connected the rig to the wellhead lies fractured on the seabed a mile below, spewing out oil at a rate at some 5,000 barrels, or 210,000 gallons, a day.

Sheen from the leading edge of the slick has surrounded island nature reserves off the coast of Louisiana and tar balls have reached as far as the Alabama coast, threatening tourist beaches further east.

Sea life has been affected in a low-lying region that contains vital spawning grounds for fish, shrimp and crabs and is a major migratory stop for many species of rare birds.

The 2.4-billion-dollar Louisiana fishing industry has been slapped with a temporary ban in certain areas due to health concerns about polluted fish.

BP, facing a barrage of lawsuits and clean-up costs soaring above 10 million dollars a day, had pinned its hopes on a 98-ton concrete and steel containment box that it successfully lowered 5,000 feet (1,500 meters) down over the main leak.

But the contraption lay idle on the seabed as engineers furiously tried to figure out how to stop it clogging with ice crystals.

BP officials were said to be considering using a smaller container that might be less prone to clogging.

Capping the leak with a smaller box would ensure the oil and seawater mixture inside the container is warm enough to prevent the formation of a slush that had clogged the larger container, according to geochemist David Valentine of the University of California at Santa Barbara.

Untold damage is already being done by the 3.5 million gallons estimated to be in the sea so far, but the extent of that harm will rise exponentially if the only solution is a relief well that takes months to drill.

Admiral Thad Allen, head of the US Coast Guard, suggested a "junk shot" was being considered to plug the main leak.

"They're actually going to take a bunch of debris, shredded up tires, golf balls and things like that and under very high pressure shoot it into the preventer itself and see if they can clog it up and stop the leak," Allen, who is leading the US government's response, told CBS television.

But experts have warned that excessive tinkering with the blowout preventer -- a huge 450-ton valve system that should have shut off the oil -- could see crude shoot out unchecked at 12 times the current rate.

There are also fears the slick, which covers an area of about 2,000 square miles (5,200 square kilometers), could be carried around the Florida peninsula if it spreads far enough south to be picked up by a special Gulf current.

"You are talking about massive economic loss to our tourism, our beaches, to our fisheries, very possibly disruption of our military testing and training, which is in the Gulf of Mexico," Florida Senator Bill Nelson told CNN.

BP began drilling a first relief well one week ago, but that will take up to three months to drill -- by which time some 20 million gallons of crude could have streamed into the sea and ruined the fragile ecology of the Gulf.