Countries that want to continue fishing in Antarctica's Ross Sea appear to be blocking the establishment of the world's biggest marine reserve.
The 25 members of the Commission for the Conservation of Antarctic Marine Living Resources have been discussing a protection proposal in Hobart, which needs a consensus between the nations to pass.
After 11 days of intense talks, the meeting is in deadlock. Some 250 representatives from the countries have until the end of Thursday to decide.
Radio New Zealand has been told that Russia, China, Japan and Korea have blocked any protection for the Ross Sea because they all want to fish there, but only light fishing would have been allowed.
The next commission meeting is due to be held about the same time next year, though it is understood that New Zealand, US, and European Union officials are trying to get it brought forward so some form of protection deal can be achieved.
Prominent marine biologist Dave Ainley, who campaigns to protect the Ross Sea, told Radio New Zealand's Nine to Noon programme on Thursday that safeguarding the sea is essential to understanding climate change.
Mr Ainley says without fishing, the Ross Sea would have to deal only with climate change and would be an "amazingly valuable laboratory" to understand how the ecosystem responds to it without other factors.
Meanwhile, protesters have staged an eleventh-hour vigil in Hobart. The Antarctic Ocean Alliance says a failure to find consensus could affect climate change research, sustainable fishing and wildlife.