The worst North Sea oil leak in over a decade has been stopped after more than a week, it has been announced.
Oil company Shell said it has stopped the leak from a flowline to the Gannet Alpha platform in the North Sea.
More than 200 tonnes of oil have entered the North Sea from the pipe since the problem was first detected on August 10.
The oil current covers around four square miles of sea, and is 3.62 tonnes by volume, according to the latest estimates.
Today, Shell divers closed the relief valve from which oil had been seeping at a rate of less than one barrel a day.
Now there will be a phase of monitoring the flowline to check that it remains sealed.
Glen Cayley, technical director of Shell's exploration and production activities in Europe, based in Aberdeen, said: "Closing the valve is a key step.
"It was a careful and complex operation conducted by skilled divers, with support from our technical teams onshore. But we will be watching the line closely over the next 24 hours and beyond.
"Our next task is to remove the residual oil from inside the depressurised flowline, and that will take time."
Meanwhile, 24 concrete mats have been laid to secure the flowline to the seabed, More will be put down in the coming days.
Shell has three vessels on site with dispersants and specialised oil spill response equipment if needed.
The company has set up an investigation team to establish the cause of the leak.
A Shell spokeswoman said: "We will also co-operate with government authorities as they conduct their own investigations, including supplying them with pipeline integrity reports and other information.
"We are continuing to monitor the conditions of the sea which affect the dispersal of the oil, in conjunction with Marine Scotland, and to undertake surveys of bird and marine life by air surveillance and vessels in the area. These surveys, which include independent bird monitoring, have indicated no significant impact on the environment."
Yesterday, Shell faced calls to make public its most recent pipeline inspection report.
The leak, which is the biggest in the region for more than a decade, was discovered on Wednesday last week but made public only on Friday evening.
On Saturday, Shell said the flow had been brought "under control".
But on Tuesday it emerged that a secondary leak was still spilling oil into the sea from the same source, although at a much reduced rate.
The following day it emerged that the first oiled bird had been discovered in the area affected by the spill near the Gannet Alpha platform, about 112 miles east of Aberdeen.
Department of Energy and Climate Change (DECC) representative Hugh Shaw, who was overseeing Shell's response, has confirmed that both relief valves on the pipeline have now been closed by divers.
There will now be a 24-hour period of extensive monitoring by subsea and aerial surveillance to check that the leak has been stemmed.
The next phase will be to stabilise the damaged pipeline and remove remaining hydrocarbons safely.
Mr Moore said: "This is clearly positive news and I would like to praise the strenuous efforts of Hugh Shaw and his team of specialists working round the clock to monitor and approve Shell's response and to keep ministers abreast of the situation.
"More work is required but it is clear that SOSREP has handled the situation well up to this crucial point, along with his team from DECC, the Maritime and Coastguard Agency, Marine Scotland and Shell.
"It is essential that such incidents are handled quickly and effectively, with minimal impact on the environment. This firm, collaborative response demonstrates that the UK regulatory regime for managing the North Sea is working well.
"Ultimately no oil leakage into our waters is acceptable and lessons must be learned.
"A thorough investigation will be carried out by the UK Department for Energy & Climate Change and the Health and Safety Executive and, if appropriate, a full report will be sent to the procurator fiscal."
Scottish Government Environment Secretary Richard Lochhead said: "It is clearly good news that Shell have managed to close the valves though the situation will need to be closely monitored over the next 24 hours to ensure this has been successful.
"In the meantime, our work to monitor the impact of the spill on our marine wildlife continues. Initial sensory tests carried out on fish samples obtained by Marine Scotland's Scotia vessel have proved clear and further scientific analysis is now being carried out.
"Initial results of the bird survey have also given no cause for concern although further monitoring is being carried out today."
Dr Richard Dixon, director of environmental charity WWF Scotland, said: "It is great to hear that the leak from the Shell platform has finally been halted.
"We hope that the next phase of the operation, to remove the oil remaining in the pipeline, is just as successful.
"Once all the threats to the environment have been removed then we should move swiftly to the inquiry, which we hope will throw some much-needed light on Shell's risky operations.
"We need to make sure that Shell and other North Sea oil companies can never again put the environment at risk like this."
Source: PAReuse content