BP has resumed drilling on a relief well, which is a part of the last step to permanently seal the ruptured Macondo well in the Gulf of Mexico.

Drilling of the relief well was halted for several weeks while BP tried other steps to kill the blown-out well. Drilling restarted following the successful installation of a lock-down sleeve, a mechanical device that secures the well’s casing hangar.

Retired Coast Guard Admiral Thad Allen, the US official overseeing the spill response, said it would seven days to complete the final kill.

The relief well has 15m to go to intercept the Macondo well near its bottom, which is about 3,960m beneath the seabed.

Following the intercept, heavy drilling mud and cement will be pumped to plug the well permanently, BP said.

Meanwhile, compensation claims related to the Gulf of Mexico oil spill are believed to be less than $20bn, which BP put into an independent claims fund.