Atlantic bluefin tuna is in crisis and clearly meets the criteria for a total ban on international trade, the head of the UN wildlife trade organisation said on Saturday.

"The secretariat believes the species (Thunnus thynnus) meets the criteria for Appendix I" of the Convention on International Trade in Endangered Species (CITES), said Secretary General Willem Wijnsteker in opening the convention's triennial meeting in Qatar.

He said this conclusion "has been confirmed by the UN Food and Agriculture Organisation and the scientific committee of the ICCAT," the inter-governmental fishery group that manages tuna stocks in the Atlantic and adjacent seas.

Delegates from some 150 countries are in Doha to review 42 proposals for tightening or loosening trade restrictions on animals and plants threatened by over-exploitation.

For Achim Steiner, head of the UN Environment Programme, "there is no question that bluefin tuna is in crisis."

But "CITES is not theatre for a conservation battle, but a platform for reasonable choices," he told journalists at a news conference.

Whether to list bluefin on CITES' Appendix I -- which triggers a ban on cross-border trade -- has emerged as perhaps the most contentious decision facing the 13-day meeting.

Japan is fiercely opposed to the measure, and is sure to mount a vigorous campaign to block the two-thirds vote needed for the top tier of protection.

Some 80 percent of Atlantic bluefin, worth billions of dollars, is exported to Japan where it is mostly served raw as sushi and sashimi.

Wijnsteker said that the fate of the gleaming, fatty fish would be debated in Doha on Thursday.

"If no solution can be found or voted on, we will form a working group to solve this issue between all countries interested in taking part," he said.

The result could be put to a vote the following week, he added.

Both the United States and the European Union support a trade ban on the open-water predator, whose stocks have plummeted by 80 percent in the Mediterranean and two-thirds in the western Atlantic.

The European Union, however, has called for delaying implementation until a November meeting of ICCAT.

This would allow Mediterranean fisheries, led by France, Italy and Spain, to go forward with the 2010 catch, which opens in May.

Japan has said that it does not believe the species is threatened with extinction, and that it will ignore the ban if it is voted into place.

1. CITES