Gulf spill 'gone' as BP claims well plug success

White House energy adviser Carol Browner said a new assessment found about three quarters of the crude – more than 152 million gallons – had been captured, burned off, evaporated or broken down chemically.

More than 205 million gallons gushed from the well, according to government estimates, after it ruptured when the Deepwater Horizon rig exploded on April 20, killing 11 workers.

"It was captured. It was skimmed. It was burned. It was contained. Mother Nature did her part," Ms Browner said.

The announcement came after BP said it had reached a significant milestone when mud forced down the well held back the flow of crude.

Workers stopped pumping mud in after about eight hours of their "static kill" procedure and were monitoring it to ensure it remained stable, BP said.

"It's a milestone," said a company spokeswoman. "It's a step toward the killing of the well."

The pressure in the well dropped quickly in the first 90 minutes of the procedure on Tuesday, a sign everything was going as planned.

The static kill – also known as bullheading – involved slowly pumping the mud from a ship down lines running to the top of the ruptured well a mile below. BP has said that may be enough by itself to seal it.

But the mud that was forced down the broken wellhead to permanently plug the gusher is only half the story. To call the mission a success, crews working on a flotilla of vessels need to seal off the well from two directions.

An 18,000ft relief well BP has been drilling for the past three months will be used later this month to execute a "bottom kill", in which mud and cement will be injected into the bedrock two-and-a-half miles below the sea floor to finish the job.

A 75-ton cap placed on the well in July has been keeping the oil bottled up inside over the past three weeks, but is considered only a temporary measure. BP and the US Coast Guard want to plug the hole with a column of heavy drilling mud and cement to seal it more securely.

A previous, similar effort failed in May when the mud could not

overcome the unstemmed flow of oil.

BP will not know for certain whether the static kill has succeeded

until engineers can use the relief well to check their work.

The task is becoming more urgent because peak hurricane season is just around the corner.

This week, the oil giant raised more cash to meet the huge cost of th clean up when it agreed the 1.9 billion dollar (1.2bn) sale of its Colombian oil and gas exploration business.

The deal will bring the funds raised by disposals to almost nine billion dollars (5.6bn) so far after it sold assets in the US, Canada and Egypt to US firm Apache two weeks ago.

BP is targeting 30 billion dollars (18.8bn) in sales after it last week revealed the spill had cost it 32.2 billion dollars (20.2 bn) so far – sending the firm to its first quarterly loss in 18 years.

The company is compensating Gulf businesses who have been hit by the spill as well as funding the clean up and rehabilitation and relocation of affected wildlife and the removal of thousands of birds and other species, including turtles, which have been killed.