BP's broken Gulf of Mexico oil well is not yet plugged for good, and work on what has been touted as the permanent solution will need to continue, the US government has said.
Retired coastguard Thad Allen, in charge of the the spill response, said officials were still evaluating the best way to finish the relief well that is part of the "bottom kill" operation. But he said that crews must move forward drilling the relief well.
"The relief well will be finished," he said. "We will kill the well."
BP had thought the mud and cement pumped in from above the leak may have essentially killed the well. But the relief well will allow engineers to pump in mud and cement from below in an attempt to seal it permanently.
Work on the wells was stopped this week because of bad weather.
The decision to resume work on the relief wells means a key milestone in the crisis that crippled the Gulf Coast's economy and ecosystem remains days away.
However, Admiral Allen has repeatedly insisted on an "over-abundance of caution" when it comes to plugging the well permanently.
Officials had been testing the pressure beneath the cement plug currently in place. Steady pressure would indicate the presence of cement in the space between the inner piping and the outer casing, which could indicate a permanent seal.
But because pressure rose during the testing, the scientists concluded that space still needs to be plugged.
It also would have been difficult to say the "bottom kill" was unnecessary after promising it for weeks as the ultimate solution, said Eric Smith, associate director of the Tulane Energy Institute.