Speculation is mounting that New Zealand and the United States will bow to international pressure and ease back on their proposal to protect the Ross Sea.
A joint bid for a 2.27 million-square-kilometre marine sanctuary in the "Last Ocean" was scuppered by Russia at a special meeting in Germany in July.
A new plan from Washington and Wellington is now expected to be submitted on Friday before talks in Tasmania next month.
Diplomatic insiders fear the revised plan could see the proposed marine protected area (MPA) slashed by as much as 40 per cent.
Opposition to the New Zealand-US sanctuary came from a bloc of fishing nations, led by Norway.
It is understood the revised draft would be in line with some demands from these countries, which include South Korea, China, Chile and Japan.
A quota of 3800 tonnes a year is in place in the Ross Sea, but the New Zealand-US plan would move boats from historic fishing grounds and spawning areas to protect the pristine environment.
In its current form, the plan would be the world's largest MPA with a 1.6 million sqk "no-take" zone, where only fishing for scientific research could take place.
A compromise to win support next month might be to strip out large areas in the north of the proposed reserve.
However, conservationists say this is an important breeding ground for toothfish, and it contains seamounts, which are habitats for organisms what could not survive elsewhere.
There is also pressure to remove the Scott Seamount from the restrictions. This is a high-productivity zone for the fishing industry.
Foreign Minister Murray McCully declined to confirm the existence of a revised draft but said there were efforts to meet other nations' concerns.
"There's been, I think, a very considered attempt to weigh up the areas of resistance expressed at Bremerhaven and to develop a strategy for the next annual meeting in Hobart that comes up in a few weeks' time," he said.
Speaking from the Pacific Islands Forum in the Marshall Islands, McCully said there have been discussions with the US and other countries, and he was prepared to accept "modifications".
"It is proving extraordinarily difficult. It was always going to be difficult and it's currently being very difficult," he said.
New Zealand Co-ordinator for the Antarctic Ocean Alliance Geoff Keey was concerned there may be a "significant reduction" in the size of the proposed reserve, but he was not surprised officials were looking at a compromise.
"We would be deeply concerned if the US and New Zealand simply revised a proposal without actually securing the support of the countries that sought changes," he said.
"If they offer too much too soon, they could end up walking away with something which really isn't an improvement on the status quo. If you keep cutting away at something, it's not worth having." The 25 member states of the Commission for the Conservation of Antarctic Marine Living Resources failed to reach agreement on two proposals at the Bremerhaven meeting. The second plan was put forward by the US and Australia.
Talks were scuppered by Russia, which called into question the legality of the negotiations.
A fresh round will take place in Hobart. Also up for discussion is a "sunset clause" that would see the MPA expire and a review undertaken.
Antarctic waters make up about 10 per cent of the world's seas and are home to almost 10,000 species, such as penguins, whales and seals.
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