A New Zealand-US bid to establish the world's largest marine reserve in Antarctica is understood to have been blocked by China, Russia and Ukraine.
It was the third time the 25 nations under the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) had failed to agree to establish a marine protected area in the fish-rich Ross Sea, 3500km south of New Zealand.
Radio New Zealand reported a consensus could not be reached despite negotiations going on into the early hours of the morning, with China, Russia and Ukraine unable to agree to the fishing restrictions and the size of the proposed 1.34 million sq km marine protection area.
New Zealand officials attending the talks in Hobart were yet to comment, but it was understood a fourth attempt to get agreement would be made this time next year.
Members of the Antarctic Ocean Alliance, which had been holding demonstrations outside the talks, were waiting to hear confirmation of the breakdown.
The proposed reserve has been scaled back from 2.27 million sq km to 1.34 million sq km after a consensus could not be found at a special meeting of CCAMLR in Germany in July.
At that meeting, nations including Japan and Norway expressed concern about the permanence of a marine reserve in the Ross Sea.
New Zealand's updated proposal included a 50-year "sunset clause", which meant the reserve could be revised or scrapped if countries felt it was not working.
Associate Professor Clive Evans, of Auckland University's School of Biological Sciences, described today's failure as a "victory for political gamesmanship and a slap on the other cheek for New Zealand, the USA and indeed CCAMLR itself from components of its body corporate".
"One wonders just how much further the original proposal will need to be diluted to gain the necessary support of all CCAMLR members should yet another modified version go forward for a fourth reading in 2014," he said.
Dr Evans said the key issues appeared to centre around the failure of certain countries to recognise the long term ecological value of conservation measures vis a vis immediate commercial gain, and the significance of the science that underpinned the current proposal.
"These matters won't be resolved on a whim.
"If some meaningful measure of protection for the Ross Sea is to be attained in 2014 without a significant loss of fishing restrictions as to make the entire proposal risible, other members of CCAMLR are going to have to do more than just lobby hard in the interim.
"Clearly the conservation message just isn't getting across."
He said while the Ross Sea ecosystem might now take a "small step backward" as the talks dragged out, it would not collapse - yet.
"There is still time to protect this unique marine ecosystem and it behoves all conservation-spirited members of CCAMLR to ensure that the fourth time really is lucky."
Lincoln University lecturer Dr Victoria Metcalf meanwhile described the impasse as saddening and troubling, "but perhaps not unsurprising".
"Negotiations between such a large number of countries and with such diverse beliefs regarding treatment of the oceans and marine biota are incredibly complex and perhaps it is a case of being patient for these MPA's to hopefully eventuate in some form," she said.
"However, in the meantime what about the marine biota in question? The cumulative impacts of fishing, climate change and ocean acidification continue to march on and there is no halt in their progression whilst talks stall again."
In particular, recent studies on the effects of ocean acidification had shown that the calcium carbonate would reach non optimal levels much sooner in Antarctic water than previously thought, just decades away.
"Thus, every year that there is added pressure from fisheries on these regions will in turn amplify the effects of other environmental variables such as ocean acidification on Antarctic marine ecosystems.
"As Antarctic marine biologists, we should be pushing for more science to be conducted to look at multifactorial impacts and these in turn need to be considered in future CCAMLR discussions."