Sydney: The Chinese icebreaker that came to the rescue of a Russian ship stranded in Antarctica, helping evacuate dozens of passengers, has signalled it may now be trapped in heavy ice, Australian authorities said on Friday.
The Xue Long -- or Snow Dragon -- has not moved for several days as it took part in multiple attempts to rescue passengers on a scientific expedition aboard the Russian vessel Akademik Shokalskiy.
The Australian Maritime Safety Authority (AMSA) said the Xue Long notified it "at 1pm AEDT (0200 GMT) this afternoon it has concerns about their ability to move through heavy ice in the area".
The Russian ship has been stuck since Christmas Eve in frozen seas, 100 nautical miles east of the French base Dumont d'Urville.
On Thursday, a helicopter from the Xue Long used a makeshift landing pad next to the marooned ship to ferry 52 scientists, tourists and journalists to an Australian government supply vessel, the Aurora Australis.
But instead of making for an Australian base, as originally planned, the ship is now waiting to see if the Xue Long itself needs assistance.
"The Aurora Australis has been placed on standby by the Australian Maritime Safety Authority's Rescue Coordination Centre Australia to remain in open water in the area as a precautionary measure," AMSA said.
AMSA said the Chinese ship would attempt to manoeuvre through the ice when tidal conditions are most suitable during the early hours Saturday, adding there was no immediate danger to those onboard.
The rescue mission was beset by extreme conditions from the start, with the Xue Long and Aurora Australis both unable to break through the ice to free the stranded Russian ship, despite several attempts.
Rain, snow and wind had also delayed plans for the helicopter rescue mission.
"This one was quite difficult to do," said John Young, general manager of the Australian Maritime Safety Authority's emergency response division.
"All Antarctic operations are difficult just because of the nature of the place and in this particular case the movement of the ice and the changing of the weather introduced their own complications."
The 52 passengers were shuttled to an ice flow near the Aurora Australis -- the Australian Antarctic Division's supply ship -- over four flights across about 14 nautical miles on Thursday.
Expedition leader Chris Turney said the evacuation was carried out "with good grace, humour and professionalism, whilst also bringing food supplies back for the Russians (we only had five day's supply left)".
"The helicopter voyage over some 14 nautical miles of jagged, broken sea ice just reaffirmed to the team how massive the ice breakout must have been that trapped us," he wrote.
"Everyone is well and in good humour -- albeit a little relieved."
Turney and his fellow passengers had been following in the footsteps of Australian Sir Douglas Mawson and his 1911-1914 expedition.
Stranded for the holidays, they greeted the New Year with cheer, singing an anthem they wrote to ring in 2014.
Giving a rousing rendition from the top deck of the Akademik Shokalskiy in footage posted on YouTube, they sang of "having fun doing science in Antarctica", only to lament in the chorus the "bloody great shame we are still stuck here".
The complicated rescue has prompted questions about the cost of the mission and whether ships should be allowed into Commonwealth Bay, where the Russian vessel became trapped.
AMSA said the costs would broadly fall to the ships involved, and it would attempt to hold a briefing with all those involved in the rescue, but that any inquiry into the conduct of the Akademik Shokalskiy would have to be addressed by Russian authorities.
"Lessons learned from those processes may be fed into the International Maritime Organisation, and the guidelines and rules it creates for polar operations which is quite an active subject... at the moment," Young said.
AMSA has said the Shokalskiy, which still has 22 crew onboard, would attempt to free herself when circumstances permitted.
"It's not an entirely risk-free environment for the ships as the ice moves," said Young of the Shokalskiy and Xue Long earlier Friday.
"And if the ice opens up and there's additional movement that creates its own issues, but both ships are constructed for the situation that they are in and the masters of both ships seem comfortable for the moment."