This week's annual meeting of the International Whaling Commission in Morocco is already its most controversial since its implementation of the 1986 moratorium on the hunting of great whales. At stake is the future of the blue whale, the fin whale, the humpback, the sperm whale and the minke. In the 20th century, 750,000 of these marine mammals were killed in the world's oceans. Yet they are still dying, at the hands of Norwegian, Icelandic and Japanese whalers who exploit loopholes in the 1986 agreement (a voluntary and temporary one, at best).

Pro-whalers claim there is no difference between killing cetaceans and domestic animals for food. This would be nonsense even if whales weren't highly evolved creatures, capable – as the latest studies show – of complex communication, abstract thought and matrilineal culture. It is impossible to guarantee the quick death of a whale at sea. Many die in agony, dragged backwards by boats to drown them. We would never countenance such treatment of agricultural livestock. Why allow it to happen to sentient marine mammals?

After three decades of increasing strain between the anti-whaling and whaling nations, it has become clear that this state of affairs cannot continue. The proposal before the IWC this week, sponsored by the US, is to allow a 10-year period of open commercial whaling, in return for Japan's agreement to reduce its take in the Southern Ocean, with a view to eventual cessation. But Japan remains intransigent, refusing to accept this compromise. They are in a position of strength – not least because they have been trading overseas aid in return for votes from IWC-registered delegates with little or no interest in whaling.

Representatives from the Marshall Islands, Cambodia and even the landlocked Laos and Mongolia – are wandering the corridors, their support bought by Japan. As a result, Japan is close to gaining control of the organisation, and insiders report that the weekend's scientific talks have come close to total collapse.

It is a question of the purists versus the pragmatists. Organisations such as the Whale and Dolphin Conservation Society (which has just released a visceral anti-whaling video narrated by Christopher Eccleston to a soundtrack by The Horrors) are lobbying vehemently against the US proposal.

But delegates from countries such as New Zealand, who support the compromise, are equally determined. "More whales will die if this proposal isn't accepted," said one adviser. He offers the nightmare scenario of Japan simply walking away from the negotiations "and killing as many humpback and fin whales as they like".

With the NGOs unable to agree among themselves (the WWF and Greenpeace support the proposal), the UK, Australia and, perhaps surprisingly, Brazil, stand accused of deliberately trying to wreck the US solution by refusing to give way. Meanwhile, Iceland has declared a self-imposed quota of 200 fin whales – 90% of which will find their way to Japan as whale meat.

It is precisely this situation that the proposal seeks to stop. But as this crucial week gets under way, we may well face the doomsday scenario. By Friday, when the IWC meeting concludes, no one will have won, and the greatest losers will be the whales, once again.