The US government has increased efforts to avert an environmental disaster as a massive oil slick leaking from a ruptured well reached the Mississippi Delat in Lousiana.
President Barack Obama last night pledged to "use every single available resource" and the US military was mobilising to help contain the spreading spill from the deepwater leak in the Gulf of Mexico.
Eleven workers are missing and presumed dead after the rig exploded 11 days ago.
The leak is pouring out crude oil at a rate of up to 5,000 barrels (955,000 litres) a day, according to the National Oceanic and Atmospheric Administration - five times more oil than previously estimated.
The rising threat has deepened fears of severe damage to fisheries, wildlife refuges and tourism in Louisiana, Mississippi, Alabama and Florida.
Louisiana Governor Bobby Jindal, whose state is still recovering from the ravages of Hurricane Katrina in 2005, warned the slick "threatens the state's natural resources." He declared a state of emergency and asked the department of defence for funds to deploy up to 6,000 National Guard troops to help with the expected clean-up.
The spreading oil is about 5km from a fragile wildlife preserve in marshland at the edge of the Mississippi Delta, which experts said would seriously damage the ecology of the area and could be very difficult to clean up.
Homeland security secretary Janet Neopolitano declared it "a spill of national significance," meaning that federal resources from other regions could be used to fight it.
Mr Obama said the London-based energy giant BP Plc was ultimately responsible for the cost of the clean-up, which has hit BP's share price and those of other companies involved in the project.
BP and the US coast guard have mounted what the company called the largest oil spill containment operation in history, involving dozens of ships and aircraft.
BP admitted struggling to control the spill, which is 1,525 metres under the sea off Louisiana's coast, and appealed for help. It has asked the Pentagon for access to military imaging technology and remotely operated vehicles to try to help it plug the ruptured well.
Reuters