A huge oil slick off the US Gulf coast is shifting its pattern and breaking up into smaller patches with open sea in between, a Coast Guard official said Friday.
More than three weeks after an explosion sank a British Petroleum (BP)-leased drilling platform in the Gulf of Mexico, the slick has yet to hit the threatened states of Louisiana, Mississippi or Alabama even though oil is gushing into the sea.
"We've had reports of tar balls which can be manually picked up, but at this point the majority of the oil is far offshore," said Admiral Thad Allen, from the US Coast Guard.
"I believe this spill is changing in its character. I don't believe any longer we have a large model spill," he told a press conference on Dauphin Island, Alabama.
Instead he explained "when the oil comes up, it's separating the different patches of oil of where you have open water between.
"There's good and bad news with that. It's widely dispersed and it's hard to manage, but on the other hand, it's coming ashore in smaller quantities of what is a larger spill."
Coast Guard officials working with crews from BP and other oil companies have been working to contain the spill and protect the shorelines, particularly Louisiana's fragile wetlands, home to a host of endangered species.
Experts have said the spill may actually be at least 10 times worse than the US Coast Guard's official estimate that 5,000 barrels (210,000 gallons) of crude are gushing from the ruptured well each day.
Without giving any new figures, Allen said the Coast Guard had been working under the assumption that more oil was spewing into the Gulf of Mexico than its own estimate.
The Deepwater Horizon rig, leased by BP and owned by Transocean, was hit by an April 20 explosion that later sank the platform, killing 11 workers.
Efforts by British energy giant BP to contain and ultimately stop the leak have so far failed, as they struggled Friday to insert either a tube into the fractured pipe to carry away the oil or place a containment box over the top.