"It is very probable that the damage exceeds that arising as a consequence of the Exxon Valdez accident regarding the extent of the contamination and the importance of the (effect on) fishing activities," said the 600-page report produced by 40 academics for the Barrie de la Maza private economic institute.

Since the Prestige broke up and sank off Spain's northwestern Galician coast in November, 78,000 tonnes of fuel residue have been scraped off beaches, according to El Pais newspaper, while the wreck continues to spew out up to one tonne per day.

The report put the cost of cleaning up the Galician coastline alone at 2.47 billion euros (2.8 billion dollars), compared with about two billion dollars for Exxon Valdez -- although damage has spread across the northern Spanish coast to France.

The Exxon Valdez supertanker went down off the coast of Alaska in 1989, spilling thousands of tonnes of oil and causing one of the worst ever environmental disasters.

The study's authors criticised the Spanish government who had "baselessly" alleged that heavy fuel still in the wreck of the Prestige would solidify over time owing to underwater pressure and low temperatures.

They said the idea of towing the Prestige to a port as recommended by several scientists rather than tow it out to sea, the eventual government option, "was rejected, among other reasons, for the social and political cost of the massive contamination" it could have caused in the near vicinity.

The report dubbed the Prestige affair a "clear warning and an example of how not to do certain things".

"We have the impression that our society and politicians still do not consider conservation and respect for nature as a real priority."

TERRA.WIRE