The US Coast Guard has said no crude oil was leaking from the oil rig which sank yesterday in the Gulf of Mexico after its platform exploded.
Rear Admiral Mary Landry said the search was continuing for 11 rig workers missing since the blast, but added that 'briefings of the survivors lead us to believe (they) may have been on the rig when the explosion occurred.'
The Coast Guard said yesterday a one-mile by five-mile slick had already settled on the surface.
Officials were working to prevent the oil from hitting land in the Gulf states of Louisiana, Alabama and Mississippi.
Experts have warned that any oil spilled from the huge Transocean Deepwater Horizon drilling rig could threaten Louisiana's fragile ecosystem that has already been stressed by hurricanes and coastal erosion.
President Barack Obama has said the federal response to the sinking of the rig is being treated as the number one priority.
The massive blast started a fire that burned for 36 hours before the structure sank yesterday.
Some 115 workers escaped, including 17 who were taken by helicopter to hospital in New Orleans after sustaining injuries.
BP has deployed a 'flotilla of vessels and resources' to the area to deal with the situation.
Transocean is the world's largest offshore drilling contractor, with a fleet of 140 mobile offshore drilling units, in addition to three ultra-deepwater units under construction.
