The worst North Sea oil leak in a decade has been stopped, more than a week after it began in a pipe to the Gannet Alpha platform operated by Shell, releasing more than 200 tonnes of oil.
The oil slick covers about four square miles of sea, consisting of 3.62 tonnes by volume, according to the latest estimates.
Shell divers closed the relief valve yesterday from which oil had been seeping at a rate of less than one barrel a day. There will now be a phase of monitoring the valve to check that it remains sealed.
Glen Cayley, the 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."
A Shell spokeswoman said: "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."