Oil valve turn-off 'success so far'
An operation to turn off a valve which was leaking oil into the North Sea has been successful so far, Shell said.
No oil has spilled into the water since Friday when divers closed the relief valve from which the substance had been seeping at a rate of less than one barrel a day.
More than 200 tonnes of oil, around 1,300 barrels, has entered the North Sea from the pipe since the problem was first detected on August 10 near Shell`s Gannet Alpha platform.
It will now carry out continuous monitoring to ensure the closure of the valve has been fully successful. The Gannet Alpha platform is about 112 miles east of Aberdeen.
An operation to lay concrete mats on the flowline to secure it to the seabed will also continue, with 27 laid so far.
In a statement, the company said: "Shell has set up an investigation team to establish the cause of the leak. We will also co-operate with government authorities and regulators 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."
Shell has faced calls to make public its most recent pipeline inspection report. The leak is the biggest in the region for more than a decade.
Last 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.
Secretary of State for Scotland Michael Moore said a thorough investigation will be carried out by the Department for Energy and Climate Change and the Health and Safety Executive and that, if appropriate, a full report will be sent to the procurator fiscal.