US oil spill a 'national' disaster

President Barack Obama started his day with a special 20-minute briefing on the disaster and pledged "all available resources," including the military, to try and stave off a possible environmental disaster.

The presence of the giant slick, now said to be growing five times faster then previously thought, just 15 miles off Louisiana's ecologically vulnerable shores dominated a White House press briefing.

"We will use all available resources, possibly including those at the Department of Defense," White House spokesman Robert Gibbs told reporters.

Homeland Security Secretary Janet Napolitano said the decision to designate the slick a disaster of "national significance" would allow clean-up equipment and resources from across the United States to be used.

The increased government urgency followed the discovery of a new leak that officials said meant a fivefold increase in the amount of oil, to 5,000 barrels or more than 200,000 gallons a day, pouring out from the debris of a sunken rig.

If large quantities of crude drift into Louisiana's marshy wetlands, which are a complex series of watery channels only navigable by boat, mopping up would be next to impossible.

It would be disastrous for natural parks full of waterfowl and rare wildlife and could also imperil the state's 2.4-billion-dollar-a-year fisheries industry, which produces a significant portion of US seafood.

As Louisiana Governor Bobby Jindal called for miles more protective booms to guard parks and fisheries in his southern state, weather experts predicted horrible weather all weekend that could seriously hamper emergency response efforts.

Jindal said NOAA reports suggested a portion of the slick, which has a 600-mile (965-kilometer) circumference, had broken off and could register a direct hit on coastal nature preserves on Thursday due to strong winds.

Rear Admiral Sally Brice O'Hara of the US Coast Guard said she expected the massive slick to make landfall some time "later tomorrow (Friday)."

Crews conducted a controlled "trial" burn Wednesday of one of the thickest parts of the slick, but heavier winds and high seas forecast through the weekend meant such operations were suspended indefinitely.

The Deepwater Horizon platform sank April 22, two days after a huge explosion that killed 11 workers.

The accident has not disrupted offshore energy operations in the Gulf, which account for 30 percent of all US oil production and 11 percent of domestic gas production.

BP, which leased the semi-submersible rig from Houston-based contractor Transocean, has been operating four robotic submarines to try and cap the ruptured well on the seabed some 5,000 feet (1,500 meters) below the surface.

Crews have failed so far to fully activate a giant 450-tonne valve system, called a blowout preventer, that should have shut off the oil as soon as the disaster happened.

As a back-up, engineers are frantically constructing a giant dome that could be placed over the leaks to trap the oil, allowing it to be pumped up to container ships on the surface.

Coast Guard Rear Admiral Mary Landry, who is leading the government's response to the disaster, warned that if the well is not secured the spill could end up being one of the worst in US history.

Should the latest figures for the spill be accurate, nearly 1.5 million gallons of crude have already spewed into the Gulf.

By comparison, some 11 million gallons of crude spilled from the Exxon Valdez into Prince William Sound, Alaska in 1989.

Two Louisiana shrimpers, meanwhile, filed a lawsuit accusing the operators of the rig -- BP, Transocean, Cameron International, and Lloyds of London, Transocean's insurers -- of negligence, seeking millions of dollars in damages.

The shrimpers are seeking class-action status on behalf of "all Louisiana residents who live or work in, or derive income from," the Louisiana coastal zone, and who have sustained damages as a result of the oil spill.

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