New Zealand's whaling commissioner Sir Geoffrey Palmer pleaded with participants in talks in the United States on Wednesday to "swallow a dead rat" and accept a controversial compromise.
Key nations including Australia and Japan, whose relations have been increasingly strained over whaling, have been meeting behind closed doors since Tuesday in Florida.
Participants are considering at a proposal that would allow Japan, Norway and Iceland to openly hunt whales, despite a 1986 ban on commercial whaling, but would also aim to reduce the total catch over the next 10 years, AFP reports.
Sir Geoffrey Palmer, a former prime minister of anti-whaling New Zealand who helped draft the compromise for the IWC, acknowledged that the proposal "will not satisfy any nation."
"It cannot. It is a compromise," Sir Geoffrey said. "To put it another way, often used in domestic politics - both sides would have to swallow a dead rat."
Sir Geoffrey said if the compromise is not accepted, then governments would not be prepared to again commit the significant diplomatic resources that have gone into the present exercise.
Australia has already said that the compromise was unacceptable and Japan has hinted it was not satisfied.
Japan kills hundreds of whales a year in the Antarctic's Southern Ocean using a loophole that allows lethal scientific research.
The compromise would bring "scientific whaling" under the control of the IWC, requiring Japan to submit DNA samples and other data to the 88-nation body.
Norway and Iceland defy the moratorium on commercial whaling altogether by lodging objections to the international decision - a practice that would be banned under the compromise.
The meeting in Florida cannot alter the 1986 moratorium but can make recommendations to the next full meeting of the IWC, to be held in June in Morocco.