Engineers moved another step towards a full shut-down of BP's disaster well in the Gulf of Mexico on Saturday after replacing a key piece of the ruptured well head, dpa reported.
Thad Allen, the retired Coast Guard admiral in charge of the crisis, said that the damaged blow-out-preventer (BOP) had been replaced.
The malfunctioning BOP is blamed for contributing to the April 20 explosion that ruptured the well head and unleashed crude oil into the Gulf of Mexico for three months. It was the worst oil spill in US history.
The ruptured 450-ton preventer is being slowly raised 1,500 metres from the seabed to a ship on the surface, where it will undergo an examination.
Since mid-July, the oil flow from the well has been stemmed through a series of measures that included a final cementing process last month.
The installation of the new blow out preventer acts as a backup to the cement and mud now plugging the well.
Full close-down of the well will be done through a so-called bottom kill procedure, possibly as early as next week. The bottom kill entails pumping cement into the bottom of the well through a relief well drilled especially for that purpose.
The BP well leaked about 4.9 million barrels of oil into the Gulf, and spawned underwater oil plumes that scientists are still studying. Much of the oil was collected by skimming and burn-offs.
The coasts of Louisiana, Mississippi, Alabama and Florida are still reeling from the ecological damage to fragile coastal lands. BP has committed to a 20-billion-dollar clean-up and damage fund to compensate for damage to the economy and the environment.
The US government has gradually reopened parts of the large area of the Gulf that was shut down for fishing out of concern for the safety of the food. At the height of the crisis, in June, 37 per cent of federal waters were closed for fishing. As of Friday, that closed area had been reduced to 17 per cent of federal waters, the National Oceanographic and Atmospheric Administration said.