Engineers from Shell were last night still working to halt the biggest oil leak in the North Sea for more than a decade, as conservationists expressed fears for the safety of young seabirds in the affected area.
The leak, which began last Wednesday at the Gannet Alpha production platform 100 miles off Aberdeen, was "under control", a Shell UK spokesman said yesterday, but had not been completely halted.
Shell estimates that about 216 tonnes of oil (more than 1,300 barrels) have escaped so far, which would make the spill the most serious in the North Sea since 2000, when about 350 tonnes were released in the Hutton field.
The Gannet Alpha leak is in a pipeline on the seabed, 300ft down, which makes repair work extremely difficult. Shell has sent down a remotely operated vehicle and divers but by last night the leak had still not been fully sealed.
As soon as the leak was detected, the well was shut down, Shell said, so the only oil leaking is that remaining in the pipe. By yesterday the rate was down to about seven barrels, a day. This contrasts with a peak of 53,000 barrels a day which gushed from BP's damaged Macondo well under the Deepwater Horizon production platform in the Gulf of Mexico last year. The full amount of oil spilled in the Gulf was between 2.2 million and 5.3 million barrels.
Shell said that rough seas over the weekend had dispersed much of the oil which had reached the surface and the area of surface "sheen" had been reduced to about half a square kilometre, from 37 sq km. The company believes it unlikely that any oil will reach the shore.
Stuart Housden, Director of the RSPB in Scotland said: "We know oil of any amount, if in the wrong place, at the wrong time, can have a devastating impact on marine life. Currently thousands of young auks such as razorbills, puffins and guillemots, are flightless and dispersing widely in the North Sea during late summer. So they could be at serious risk if contaminated by this spill."