An American heavy icebreaker is leaving Australia for Antarctica to rescue more than 120 crew members aboard two vessels trapped in ice near the frozen continent's eastern edge.
The Polar Star - a 399ft coastguard cutter - will be helping Russian and Chinese ships because "there is sufficient concern that the vessels may not be able to free themselves from the ice", the coastguard said.
The Russian research ship - Akademik Shokalskiy - has been trapped in ice-clogged Commonwealth Bay since Christmas Eve, while the Chinese ship which came to its rescue, Xue Long (Snow Dragon) reported on Friday that it too had become stuck nearby.
A day earlier, the Chinese ship's helicopter had retrieved 52 scientists, journalists and tourists from the Russian ship, who are now on their way home aboard an Australian icebreaker, Aurora Australis.
Authorities say the 101 crew aboard the Chinese ship and 22 aboard the Russian ship had plenty of supplies and were in no immediate danger. The Polar Star has cut short its planned stop in Sydney, Australia, to assist.
It will take about seven days to reach Commonwealth Bay, depending on weather.
The rescued passengers are now aboard the Australian icebreaker Aurora Australis, seen from the rescue helicopter in the photo below:
Aurora Australis has advised AMSA that the 52 passengers from the Akademik Shokalskiy are now on board.
Crew members from the stranded research vessel Akademik Shokalskiy have been giving thanks after arriving safely on an Australian rescue ship.
The expedition leader Professor Chris Turney tweeted:
Guardian journalist Alok Jha was also full of praise for their rescuers:
We've made it to the Aurora Australis. Via a v big helicopter from Xue Long. Thank you to everyone who has helped w this amazing operation
All but four passengers from the research vessel stranded in the Antarctic have been safely transferred to an Australian icebreaker, according to the Australian Maritime Safety Authority (AMSA) which is coordinating the rescue effort.
AMSA has received confirmation that 48 passengers from the Akademik Shokalskiy are now on board the Aurora Australis.
The second team of people stranded in the Antarctic have been airlifted from the ice by a Chinese rescue helicopter, according to expedition leader Professor Chris Turney.
The helicopter from the Chinese icebreaker Snow Dragon will take all the passengers from the ice-bound Akademik Shokalskiy and transfer them to an Australian Antarctic supply ship, the Aurora Australis.
First passengers from Shoklakiy have taken off, now on their way to Aurora Australis http://t.co/PS4uOndHX4
The helicopter from a Chinese icebreaker has arrived to help evacuate passengers and crew from the stranded Akademik Shokalskiy ship.
Professor Chris Turney posted footage of the helicopter arriving on the group's YouTube account.
A Chinese rescue helicopter has arrived to rescue passengers from a ship trapped in ice at the Antarctic, a passenger has said.
Expedition leader Professor Chris Turney tweeted a helicopter had arrived to rescue the 74 passengers on board.
Fifty two scientists, journalists and tourists, along with 22 crew members, have been trapped in sea ice on the Akademik Shokalskiy since Christmas Eve.