LONDON (Reuters) - Oil major Royal Dutch Shell said a large volume of oil remained in its leaking pipeline, raising the possibility that Britain's worse oil spill for a decade could worsen, but said the extra amount would only seep out in a worse case scenario.
Oil leaked into the sea off the coast of Scotland for a seventh day on Wednesday as Shell said it was planning extensive activity including the deployment of divers to completely stop the flow of oil.
The company told reporters on a conference call its estimate of the total volume of oil which had leaked remained at just over 218 tonnes, in line with a figure given on Monday, as oil continued to trickle out at the rate of one barrel a day.
Up to 660 tonnes could remain in the pipeline at the Gannet field, however, said Glen Cayley, technical director of Shell's European exploration and production activities, and the company was focusing on how to deal with it.
"Containment options are also being progressed as a longer-term option," he said.
The Gannet platform, which Shell co-owns with U.S. oil major Exxon Mobil Corp, was due to be shut down for 30 days on Thursday as part of Shell's routine maintenance schedule and this shutdown would go ahead, giving the company the chance to investigate other pipelines connected to the field, Cayley said.
Shell said it needed to improve its inspection policies.
"We're making every effort to improve our inspection program and revisit our maintenance priorities," Cayley added.
The UK government said in a statement on Wednesday it believed the leak was under control.
"Although the spill was deemed as significant, our information is still that the oil is not expected to reach the shore, and that it will be dispersed naturally," said Hugh Shaw, the secretary of state's representative for maritime salvage and intervention.
Reporting by Sarah Young; Editing by David Holmes