An American heavy icebreaker is leaving Australia for Antarctica to rescue more than 120 crew members aboard two vessels trapped in pack ice near the frozen continent's eastern edge.
The Polar Star, a 399ft coastguard cutter, had a request from Australia, Russia and China to help the 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.
"Our highest priority is safety of life at sea, which is why we are assisting in breaking a navigational path for both of these vessels." Vice Admiral Paul Zukunft, the coastguard Pacific Area commander, said. "We are always ready and duty bound to render assistance in one of the most remote and harsh environments on the face of the globe."
The Australian Maritime Safety Authority's Rescue Co-ordination Centre, which oversaw the rescue, said the Polar Star, the US Coast Guard's only active heavy polar icebreaker, would leave Sydney today after taking on supplies.
It will take about seven days to reach Commonwealth Bay, depending on weather.
After the Snow Dragon reported it was stuck on Friday, AMSA told the Aurora to stay in the area, with its rescued passengers on board, in case help was needed. Under international conventions observed by most countries, ships' crews are obliged to take part in such rescues and the owners carry the costs.
Yesterday AMSA said the Aurora was allowed to continue and the Chinese and Russian ships were safe.
Andrew Peacock, an Australian doctor and photographer who was rescued from the Russian ship, said he and his fellow passengers "have been and continue to be thankful for all the help we have been given and ... aware of the cost and inconvenience to others".
"Handwritten notes of gratitude from each person rescued have been scanned and faxed to the captain of the Chinese ship and Chinese authorities and we remain concerned for that ship and the Akademik Shokalskiy which remain in the ice and we fervently hope that the Polar Star gets there quickly to free those vessels and their crew."
The Polar Star left its home port of Seattle in early December to take part in one of its main missions, Operation Deep Freeze, to break a channel through the sea ice of McMurdo Sound to resupply and refuel the US Antarctic Programme's McMurdo Station on Ross Island.
A reporter for China's official Xinhua News Agency aboard the Snow Dragon, Zhang Jiansong, said an iceberg appeared over Thursday night and blocked the ship's return route.
He said the ship would again try to find a way out, possibly as early as tomorow, when westerly winds would hopefully loosen the ice's grip. The Snow Dragon was 13 miles from open water, he said.