Japan has threatened to resume commercial whaling after a suspension of more than 20 years, in a gesture of defiance towards conservationists and antiwhaling governments.

The threat came with a demand for progress at the International Whaling Commission talks in Chile this week. The unexpectedly blunt ultimatum follows a winter whaling season of high maritime drama and bitter diplomatic rows.

In light of Japan’s threat, some fear that the commission may be in danger of total collapse unless it can rebuild its function as a constructive forum for debate on the whaling issue.

Critics of the commission’s structure - and of the susceptibility of less-wealthy nations to persuasion by richer ones such as Japan - believe that it has already been undermined. In 2006, and under Japan’s clear initiative, the commission narrowly passed a motion declaring the 1986 moratorium on commercial whaling “no longer necessary”.

In response the antiwhaling movement has grown progressively more activist. Japan’s supposedly “scientific” whaling fleet hunted its prey in the Southern Ocean under the near-constant scrutiny and sabotage efforts of groups such as Sea Shepherd and Greenpeace. The final catch, of 550 minke whales, was a little more than half of the planned haul.

The chaotic scenes on the high seas - which included several exchanges of homemade missiles - marked the peak of a steady escalation by both the whalers and the activists. Japan is reluctant to yield any ground on its perceived right to hunt whales, believing that the compromise would open the door to other legal restraints on its extensive tuna-fishing activities.

The activists decry Japan’s long-standing exploitation of the 1986 moratorium on commercial whaling. The whales harpooned by the Japanese fleet are caught under its right to pursue lethal scientific research: many environmentalists claim that Japan’s Cetacean Research Institute has yet to publish any meaningful findings after two decades of data collection and that the meat from the scientific catch is sold commercially.

The resulting spat between Japan and the most vocal antiwhaling governments, especially Australia, has all but dashed hopes of any serious breakthroughs at the main commission meeting in Portugal next year, sources in Tokyo say.

Members of the commission are meeting for interim talks this week in Santiago and passions are already flaring. Even before the 80 members sat around the table, Tokyo had threatened to leave the commission.

Japan is eager to restart small-scale whale catches within its waters, claiming that many fishing communities have historically depended on them and that the hunts are a piece of cultural tradition.

One Japanese official argued that the debate on commercial whaling had been obscured by misunderstandings about the size of whale populations.

“Sometimes people opposed to hunting say that the whales are in peril,” he said, “but that is like saying birds are in peril.”

A government spokesman said that if, as is widely expected, Japanese ambitions are opposed fiercely by the antiwhaling lobby and talks collapse before next year, Japan would “review our relationship with the IWC, and possibly resume whale catches in our own way”.

The conflict has prompted some countries, including the United States, to suggest forming a separate committee to discuss Japan’s proposal to resume whale hunting in its waters.

Hope for the continued stability of the whaling commission may rest in Calestous Juma, a Harvard professor and adviser to the group with a special mission to calm the factions down and encourage progress.

“I am actually quite confident that when this process starts, we will find a lot of areas for compromise,” he said, insisting that the pro and antiwhaling camps had more in common on issues of conservation and protection of global whale stocks than either realised.

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