An oil slick covering 400 miles is threatening a slow-motion catastrophe for the Gulf of Mexico’s delicate marine life, with 42,000 gallons a day now gushing from an uncapped well after a rig explosion.

Two days after declaring that there was no leak and that oil on the surface was residue from on board the Deepwater Horizon drilling platform that burst into a fireball on Tuesday, officials said the slick was coming from the seabed and was now 25 times the size it was on Friday.

"It’s 1,000 barrels (a day) emanating from 5,000 feet below the surface," said Rear-Admiral Mary Landry, of the U.S. Coast Guard, who is overseeing the emergency response. "Absolutely, this is a very serious oil spill."

BP, which leased the rig, said last week that it was doing everything in its power to contain the spill and resolve the situation "as rapidly, safely and effectively as possible," using underwater robots, 700 personnel, five aircraft, 32 vessels and nearly 200 miles of floating booms.

One third of the global supply of oil dispersant is ready to be deployed.

Click here to read more on this story from the Times of London