The proposal seeks to legitimise commercial hunting in exchange for a drop in the number of whales killed by Japan, Norway and Iceland, who all claim exemptions to the ban.
"Japan may kill a few less whales, but Norway and Iceland would in fact end up being allowed to kill more"
Japan, Norway and Iceland continue to flout the 24-year moratorium, tracking and killing thousands of whales each year.
The IWC hopes the compromise proposal, to be debated by 88 pro-and anti-whaling nations, will end unrestricted whaling, including of species on the verge of extinction.
The draft deal proposes reduced annual catch numbers through 2020 for four species of whale as a baseline for negotiations, in a bid to bring the three whaling nations back under the agency's control.
Under the scheme, total allowable kills in each of the first five years would be just over 90 per cent of the 2008-2009 figure of about 1,500, dropping further from 2015 to 2020.
Claire Bass from the World Society for the Protection of Animals told Al Jazeera the compromise deal "completely undermines the whaling ban which is one of the most important conservation and animal protection measures of our time".
"Japan may kill a few less whales, but Norway and Iceland would in fact end up being allowed to kill more. Primarily we are concerned with the welfare problems of whaling. It is such a grossly unacceptably cruel industry and it just shouldn't be allowed in the 21st century," Bass said.
Even the IWC's own scientific committee, which has met over the last two weeks, is set to say that numbers proposed under the compromise are not sustainable, committee members said.
Scientists calculated that the proposed catches were several times too high for the western North Pacific Bryde's whales, and double the tolerable limits for both North Atlantic fin whales and eastern North Atlantic minke whales.
Only for the central North Atlantic minke whales were the tabled suggestions well under conservation-safe limits, they said.
The new figures "don't correspond to a scientific reality," Jean Benoit Charrassin, a researcher at France's Museum of Natural History and a long-standing IWC scientist, said.
The proposal pays lip service to advice from the scientific committee, but the IWC has yet to adopt methods its experts laid out in 1994, in a so-called Revised Management Procedure [RMP] on how to calculate safe limits and verify they are respected, he said.
The World Wide Fund for Nature (WWF), said a compromise was needed to end the exemptions claimed by the three nations, but said "we will not support a compromise at any cost".
Advocates say 5,000 whales will be saved over the 10-year life of the deal but opponents say the proposal would legitimise hunting for profit and throw a lifeline to a dying industry that has constant confrontations with environmental groups on the world's oceans.
They also say the draft leaves open the question whether whale meat and other whale products can be traded internationally.
The compromise formula has also been criticised by Australia, which has launched a complaint against Japanese whaling at the International Court of Justice in The Hague in the Netherlands, the UN's highest court.
"The Australian government cannot accept this proposal as it currently stands," Peter Garrett, the country's environment protection minister, said.
The German parliament urged its government to reject the proposal, saying "we can only guess at how fatal the consequences will be for marine ecosystems".
The United States also has voiced reservations, especially over the number of whales the three countries would be allowed to hunt.
However, Patrick Ramage of the International Fund for Animal Welfare, said he is concerned that the US is too anxious for a deal, partly because it fears Japan could veto the approved catch by Alaskan Inuit hunters, which falls under a clause allowing Aboriginal subsistence whaling.
"The quotas have more to do with political science than biological science," Ramage said.
"There have been decades of steady progress in conservation. All of that is threatened with reversal by a politically expedient proposal that some governments are trying to rush through," he said.