Although the investigation, led by scientists and engineers from BP, is in its early stages, it is understood that bacteria that live on oil sludge in the pipelines caused the rapid corrosion of more than 16 miles of steel pipe.

“This bacteria and the sludge is the key to this mystery of the cause of this corrosion,” a BP spokesman said. “We never anticipated this kind of build-up of solids in the pipeline, or that this bacteria would live there.”

While only five holes have been found so far, the BP investigation has identified as many as 16 potential holes.

The oil company reckons that the replacement of more than 20 miles of transit pipelines in Prudhoe Bay could cost about $100 million (£53 million).

Much greater is the financial impact from the loss of BP’s quarter-share of Prudhoe Bay’s 400,000 barrel per day output, representing about $7 million per day in revenue forgone. BP is expected to learn today from regulators whether it can continue to pump oil from the western side of the oilfield during repair work.

Kurt Fredriksson, commissioner of Alaska’s Department of Environmental Conservation, told The Times: “We have regularly checked this line and the corrosion crept up on us much faster than anyone imagined.”

Frank Murkowski, the Governor of Alaska, instituted a state-wide hiring freeze on Wednesday to help to stem a shortage of skilled workers to fix the leaking pipe.

He said that the state attorney-general would investigate Alaska’s “right to hold BP fully accountable for losses to the state”.

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