In a recent report Annan said "there is still uncertainty about the long term damaging effects of trawling (...) and serious research is urgently needed." He added that the "precautionary principle" should be applied to the practice.

The UN's Food and Agriculture Organisation (FAO) says bottom trawling accounts for just 0.5 percent of global fish catches but causes serious environmental damage.

Trawlers using the technique lower long pocket-shaped nets weighted down with metal rollers and scraping devices onto the sea bed up to 1,000 metres (3,000 feet) below.

These are then dragged along the sea floor, ripping up and shredding everything in their path.

"The carnage doesn't make sense. High seas bottom trawling is causing ecological destruction that is grossly disproportionate to its very limited economic contribution," says the Deep Sea Conservation Coalition (DSCC), an umbrella organisation of environmental groups and scientific bodies committed to preserving deep sea habitats.

"What a luxury and what a waste, when 80 percent of what is dragged up from the sea is thrown away," said Ibrahim Thiaw, Director General of the World Conservation Union (IUCN).

The environmentalists say the practice is disastrous for many forms of slow-growing marine life on ocean floors, including a number of fish and coral species.

Speaking at the United Nations on Friday, the vice-president of the tiny Pacific state of Palau, Elias Camsek Chin, called bottom trawling "an irresponsible practice, at the origin of 95 percent of the damage done to underwater mountains."

Palau, Japan, the United States, Norway and Australia have already banned the practice in their territorial waters.

But when it comes to the high seas, which are not covered by national jurisdictions, bottom trawling still takes place.

"Deep water habitats are extremely vulnerable and need this kind of protection," Annan wrote in his report.

Australia intends to push for a total ban on bottom trawling in international waters by the end of 2007.

It also wants regional fisheries watchdogs to ensure the measure would be respected in their respective jurisdictions "at least until it can be scientifically proved that these activities do not affect the fragile marine ecosystem."

But the European Commission, which overseas fish catches in EU waters, implicitly admitted it would be hard to enforce a ban.

EU Fisheries Commissioner Stavros Dimas told AFP that EU governments favoured banning high seas bottom trawling "on a case by case basis." The approach was "not enough" but better than nothing, he said.

Remi Parmentier of the DSCC remained optimistic however.

"Nothing has been set in stone," he said. "The EU is divided but more and more European countries are in favour of a moratorium," he continued.

"The EU has committed itself to reducing its environmental impact around the world: it has an excellent opportunity to do this on the high seas, which make up a considerabl part of the planet."

Tom Pickwell of environmental campaigners WWF was similalrly upbeat.

There were still "very good chances" that a moratorium would be approved, he said.

"Many countries who want a sustainable fishing industry realise that, in the long term, their business is at stake," he added.

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