An optimistic assessment of the way that the weather has dispersed the Braer's cargo of 84,500 tonnes of light crude was given by Dave Bedborough, of the Department of Transport's Marine Pollution Control Unit, yesterday.
He said: 'The east coast is free of any oil. There are some general light sheens around Sumburgh Head but working down from the north the remaining traces are beginning to break up.'
Although there is still some oil close to the wreck, the amount of spillage visible had dropped by 80 per cent since the previous day, Mr Bedborough said. He estimated that one-third of the cargo had evaporated and the rest had diluted.
Captain George Sutherland, director of marine operations for the Shetland Islands Council, added: 'There is a very substantial reduction in the amount of visible oil around the whole of the west side of the Shetlands.'
But environmental groups challenged this view as complacent. Alison Ross, a spokeswoman for Greenpeace, said: 'It is quite wrong and totally irresponsible to imply that this oil has suddenly disappeared from the environment . . . there is still a huge amount of oil in the environment. The visible measure is not an adequate one.' She said that the dispersal of oil would make it more easily absorbable for small marine life which form the base of the food chain.
Dr Sian Pullen, Marine Conservation Officer of the World Wide Fund for Nature (WWF), said: 'I think we have been remarkably lucky with the short- term effects because the sea and the winds are actually doing a remarkable job of dispersing the oil. But we don't know what the effect of 84,500 tonnes of oil . . . is going to have on the very bottom of the food chain.'
The Duke of Edinburgh, who visited the islands with the Prince of Wales yesterday, and who is WWF's international president, said: 'It looks a lot better but it is very, very difficult to know what is going on out of sight.'
Divers from the Dutch salvage company Smit Tak do not expect to be able to get on board the wreck until tomorrow.