A government research chief yesterday told MPs and peers that the Brent Spar should have been sunk in the deep ocean.
Professor John Krebs, director of the Natural Environment Research Council, said it would be a mistake to close the door on sea dumping of other North Sea oil and gas structures.
In a briefing at the Houses of Parliament, Professor Krebs said the research council's senior marine scientists had concluded that the environmental damage caused by sinking the gigantic oil storage buoy nearly 8,000 feet in the north-east Atlantic would have caused very limited environmental damage, all confined to the deep ocean.
Worms, molluscs and crustaceans on an area roughly equivalent to two football pitches would have been wiped out by the impact of the plunging Spar and the spread of sediment.
On shore disposal, which the Brent Spar's owner Shell is now planning, poses greater risks to the environment and human safety, Professor Krebs said.
Shell was forced to make a U-turn last month in the face of a consumer boycott in Germany and protests from several European governments.
"We don't want to set a precedent for ruling out the deep ocean as a waste disposal option," Professor Krebs said. Even if Shell had wildly under-estimated, by a factor of 10, the quantities of oil, radioactive salts and toxic metals inside the redundant Spar, deep sea dumping would still not pose a significant environmental threat.
Tim Eggar, the trade and industry minister in charge of North Sea oil, told the briefing that Shell would now have to bring forward highly convincing arguments to gain his permission for onshore scrapping of the Spar, having earlier persuaded the Government that deep sea disposal was the best practicable environmental option.
He said the oil giant would have to demonstrate how the real hazards to the environment and human safety involved could be eliminated.
"It simply should not be assumed that the option of deep-sea disposal has been eliminated," he said.
Mr Eggar blamed Greenpeace's "emotional and simplistic" campaigning and European ministers bowing to the environmental group's pressure for the Brent Spar fiasco.
The research council says it initiated the briefing to spell out the scientific basics to peers and MPs. It was never consulted by any of the government departments dealing with Shell's case for sea dumping the 14,500- tonne Brent Spar.
t Late last week the Ministry of Defence admitted, in a parliamentary written answer, that it had sent Royal Marines to the Kinross air base in Scotland as part of contingency plans for military involvement in ending Greenpeace's occupation of the Brent Spar.