Britain's growing passion for take-away raw fish looks like wiping Japan's most famous cuisine off the menu as worldwide fish stocks strain to meet the demands of "supermarket sushi".

The founder of Britain's first conveyor-belt sushi restaurants told a forum of Japanese chefs and food suppliers yesterday that the appetite they had stimulated was not sustainable.

The warning came as, only a few miles across Tokyo, representatives from the 13 nations who consume the most tuna met scientists to discuss chronic overfishing and the possible extinction of sushi's most critical ingredient.

High on their agenda, said insiders at the closed-door talks, was the explosive "sushi effect" on national eating habits around the world. The talks, which end today, are expected to result in a global agreement to tighten fishing rules.

Caroline Bennett, the founder of the Moshi Moshi sushi chain, said that expanding global appetites for sushi and the rapid emergence of fast-food sushi would not be met by the available natural resources.

While she applauded the speed with which Britain has developed a taste for a well-rolled tekka-maki, she questioned its role as anything other than an occasional treat.

"Can the sea really let us eat sushi in these numbers?" she asked, adding that London now had more than 300 Japanese restaurants and the British market for Japanese food is worth more than £500 million a year.

The problem is not restricted to rising appetites for sushi in Europe and the US. Although Japan is, by a long way, the world's most voracious consumer of tuna, it has met a potentially hungrier rival in the economically blossoming China. Japanese buyers unhappily report the growing phenomenon of kai-make or "deal-blowing" where the Chinese have snapped up the very best tuna at prices that Japan is not prepared to pay.

Ms Bennett was talking to members of the JRO ¨C an organisation formed to promote Japanese restaurants abroad. Opposing plans for a global "sushi police" who would issue authenticity certificates, the JRO hopes instead to help to train nonJapanese chefs working in supposedly Japanese restaurants. The fewer stomach upsets that result from people eating badly made Japanese food, runs the JRO's logic, the better will be the global reputation of Japan and its national dishes, especially the ones served raw.

But the efforts of the JRO may be in vain. The 13 nations that met yesterday were left in no doubt that current levels of fishing and persistent violation of existing rules would end in disaster. Fisheries operators in the Mediterranean, where bluefin tuna quotas are regularly flouted, were opposed to the idea of tighter regulations.

The International Commission for the Conservation of Atlantic Tunas, which also gathered at the meeting, is expected this year to issue a master-plan for increasing world tuna stocks. Some, including the United States, believe that the only solution lies in a temporary ban on all tuna catches.