The Food and Agriculture Organization said that conservation effort must be improved, but that it was "unlikely" there would be no seafood on consumers' plates by mid-century, calling the report "statistically dangerous".

"Such a massive collapse ... would require reckless behavior of all industries and governments for four decades, and an incredible level of apathy of all world citizens to let this happen, without mentioning economic forces that would discourage this from happening," said Serge Michel Garcia, director of the FAO's fishery resources division.

South Korea's fisheries ministry labelled the report "too radical," and said more scientific data was needed before heeding the call of environmentalists like Greenpeace to set aside 40 percent of oceans as marine reserves.

The cry for urgent action came in the wake of a report published in the November 3 issue of the US journal Science. In the most exhaustive study conducted to date, US and Canadian researchers warned that overfishing and pollution threatened the accelerated loss of ocean species, ecosystems and human food supplies.

The worldwide fishing industry currently extracts some 90 million tons of fish each year from the worlds ocean's, according to the FAO. It represents a significant economic sector in many countries, including Scandinavia nations, where officials expressed skepticism on the report's conclusions.

"I don't think the oceans will be empty in 50 years time," said Helga Pedersen, the Norwegian minister of fisheries.

"That said, we have to work harder to secure sustainable management of fish stocks," she added.

Nordic fishing unions said industrial overfishing was not, in any case, the main culprit. "Sure there are threatened species, but pollution is the main problem," said Lena Talvitie, vice-president of the Finnish federation of professional fishermen.

Britain conceded that the plundering of fish from the seas posed the most serious environmental challenge after global warming, the British secretary of state for fishing Ben Bradshaw told the BBC.

But as the fourth-biggest fishing country in Europe after Spain, Denmark and France, Bradshaw also defended London's record on clamping down on illegal fishing and setting quotas. He rejecting any moratorium on cod fishing.

"If there were a zero catch for cod, we would have to close almost all of the UK fishing industry because there's almost no part of our fishing industry that doesn't catch some cod as by-catch," he said.

The economic impact of massive conservation efforts would be felt from the shores of Britain to Japan, which is the world's largest consumer of fish.

For environmentalists, however, the report's message was unequivocal.

"Overfishing and pirate fishing are destroying our oceans at an alarming rate," said Greenpeace spokesman Nilesh Goundar in Australia.

Twenty-nine percent of 8,000 fished species were considered "collapsed" in 2003, that is, their catches had declined by 90 percent or more," Boris Worm of Dalhousie University in Canada, lead author of the report.

The European Commission reacted by urging better international cooperation to turn around any doomsday scenario on the world's marine fish supply.

The good news, said Mireille Thom, spokeswoman for European Fisheries Commissioner Joe Borg, is that biologists believe that "if we act on overfishing, the ecosystems could come back to life".

"The measures are already in place but international cooperation must be strengthened to put an end to illegal fishing, which is an international problem," said Thom.

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