Much of the Atlantic bluefin is turned into Japanese sushi
France has added its voice to calls for a ban on the global trade in bluefin tuna, the numbers of which have dwindled through overfishing.
France wants a ban after an 18-month delay to allow scientists time to study the data on tuna stocks, Environment Minister Jean-Louis Borloo said.
The bluefin tuna trade might be curbed at world conservation talks in March.
France is among the Mediterranean countries that fish bluefin tuna for export to Japan, the main market.
France's tiny neighbour Monaco is leading the push to get bluefin tuna added to the list compiled by the Convention on International Trade in Endangered Species (Cites). Italy has also backed the call.
But Mr Borloo said "there is still powerful international lobbying from a big country, which has allies" - a veiled reference to Japan, which takes about 80% of the bluefin tuna catch from the Atlantic and Mediterranean.
Conservationists say bluefin numbers have fallen to about 15% of their pre-industrial fishing levels.