Conservation groups say international whaling talks may stall without the involvement of a key broker.
The chairperson of the International Whaling Commission, Cristian Maquieira, has withdrawn from next week's meeting in Morocco because of ill health.
Under the compromise deal proposed by Mr Maquieira, Japan would agree to reduce the number of whales it takes in the Southern Ocean in return for its whaling programme being legitimised.
The executive director of Greenpeace New Zealand, Bunny McDiarmid, says it is unfortunate he has pulled out because the deal has taken two years to hammer out between 12 whaling and anti-whaling countries.
Ms McDiarmid says the deal is not yet acceptable, but still holds promise for protecting whales.