Plans to create two vast ocean sanctuaries in Antarctica to protect the pristine wilderness failed Friday for a third time, with Russia and China blocking the bids, delegates at multi-nation talks said.

The proposals for two huge Marine Protected Areas were on the table at the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) meeting in Hobart, which brought together 24 countries and the European Union.

But the 10-day talks ended with the nations unable to agree to a US-New Zealand proposal for a protected zone in the Ross Sea and another by Australia, France and the European Union for a sanctuary off East Antarctica.

"The international community came together in Hobart to protect key parts of the Antarctic Ocean -- one of the last pristine environments in the world -- yet Russia chose to stand in the way," said Joshua Reichert, executive vice president of US-based Pew Charitable Trusts, which had a delegate inside the talks.

There was no immediate comment from the Russian side, while China's foreign ministry spokeswoman Hua Chunying said she was unaware of the specifics of the case.

Environmentalists said an ocean wilderness that is home to 16,000 known species, including whales, seals, albatrosses, penguins and unique species of fish, was at stake.

CCAMLR -- a treaty tasked with overseeing conservation and sustainable exploitation of the Antarctic Ocean, also known as the Southern Ocean -- has not yet made any official comment.

The head of the Swedish delegation Bo Fernholm said the outcome was disappointing.

"There was sadness," he told AFP. "We were quite unhappy with the fact that it didn't go ahead, that they couldn't get it through now was a disappointment."

Another delegate, who did not want to be named, confirmed the details.

"The talks have failed. Russia and China wanted more details, more time. It's very disappointing," he told AFP.

The sanctuaries required the support of all 25 members of CCAMLR to be passed. Despite the scale of the New Zealand-US proposal being reduced, Russia was not won over.

While Russia and Ukraine actively blocked both proposals, China withdrew support for the East Antarctic sanctuary, said the Antarctic Ocean Alliance, a coalition of high-profile individuals such as actor Leonardo DiCaprio and conservation groups.

It was the third attempt since 2012 by CCAMLR to protect large areas in the Southern Ocean. Fernholm said while "substantial discussions" took place, Russia had reservations, believed to be related to the limits on fishing.

"I think there are some major problems remaining on some of the major things like how long does a marine protected area need to stay in force, and there were also objections about the size of these marine protected areas," he added.

The US-New Zealand bid for a sanctuary in the Ross Sea, the deep bay on Antarctica's Pacific side, had been considered the best hope after its size was reduced, with its no-fish zone to be 1.25 million square kilometres (480,000 square miles).

The second proposal called for a 1.6 million square kilometre protected zone off East Antarctica, on the frozen continent's Indian Ocean side.

Their creation would make the largest marine protection areas in the world.

Andrea Kavanagh, director of The Pew Charitable Trusts' Southern Ocean sanctuaries project, said safeguarding the teeming marine life of the Antarctic had far-reaching consequences for the world's oceans.

"This is a dark day not just for the Antarctic, but for the world's oceans," she said.

"The scientific basis to create these reserves is overwhelming. The stubborn self interest of a few should not be allowed to deny the will of the majority of countries around the world."

Environmentalists said CCAMLR's conservation mandate had been brought into question.

"What we have witnessed over the last few years is the steady erosion of the spirit and mandate of CCAMLR to conserve our last intact ocean ecosystem remaining on earth," said Farah Obaidullah from Greenpeace International.

"This year's failure denigrates the reputation of CCAMLR and is symptomatic of a dangerous global trend where corporate and political interests override any genuine efforts to protect the oceans for the sake of future generations."