The technique is completely unregulated in extensive areas of the world's high seas because most seamounts are located beyond the reach of national laws, according to the Deep Sea Conservation Coalition.

The grouping includes the Natural Resources Defense Council, Greenpeace International, The World Conservation Union, Conservation International and WWF International.

The coalition announced its push for a global ban at the start of this week's informal U.N. consultations in New York on oceans and the Law of the Sea.

Eleven nations - Denmark, Estonia, Iceland, Japan, Latvia, Lithuania, New Zealand, Norway, Portugal, Russia and Spain - took 95 percent of the fish caught in bottom-trawl fisheries on the high seas in 2001, the most recent year for which figures are available, fisheries expert Matthew Gianni said.

The practice accounted for sales of $300 million to $400 million of fish that year out of a total annual market of some $75 billion, he told reporters.

While there may be as many as 50,000 seamounts dotting the ocean floor, fewer than 1 percent have been studied. But scientists believe the habitat to be generally extremely rich in highly diverse marine life.

The coalition argues a bottom-trawling ban should be imposed until seamounts can be scientifically assessed and legal schemes put in place to protect them.

"Bottom trawling is eliminating entire ecosystems and species; in some cases, before we have even learned of their existence," said Karen Sack of Greenpeace International, who spoke to the news conference via a live feed from the deck of the group's vessel, the Rainbow Warrior.