A Chinese ship that helped rescue passengers from a Russian vessel trapped in Antarctica only to get stuck in the ice itself has broken free.
The Xue Long, or Snow Dragon, "pulled free of the ice and navigated into the open waters", said the official Xinhua news agency, which has a reporter on board the vessel.
The icebreaker had been trapped in the thick Antarctic floes since last Friday, and a westerly wind had been expected to give it its best chance of escaping, according to the China Daily newspaper.
The wind was expected to help push away some of the heavy ice surrounding the ship, according to Xinhua, which noted that the biggest floes were three times thicker than its ice-breaking capacity.
The Xue Long's helicopter last Thursday ferried 52 passengers on the stranded Russian ship Akademik Shokalskiy, which had been trapped for 10 days, to the safety of an Australian vessel.
The 52, who spent Christmas and New Year stranded aboard the ship in Antarctica's Commonwealth Bay, were due to arrive at Australia's Casey research base Tuesday night, with a return to Australia expected in two weeks.
"Its performance, especially the success in rescuing all the passengers, has been given the thumbs up by global public opinion," China's Global Times said in an editorial on the Xue Long's rescue of the Shokalskiy passengers. "China should be proud of it."
"Xue Long's mission is an epitome of China's attitude toward its international obligations," it added.
The Chinese ship afterwards became surrounded by ice itself, and an effort to break free early Saturday was unsuccessful.
It has 101 people on board, while 22 crew remain on the trapped Shokalskiy.
The ice surrounding the Xue Long was up to four metres thick, with the nearest open waters 21 kilometres away, Xinhua reported.
But it added that the Chinese ship, which includes a gym, movie theatre and ping-pong tables among its facilities, has enough food to last until April and enough fresh water for the next month.
In recent days, it had prepared for a breakout by warming up its engine and creating a channel about one kilometre long and described as an "ice-breaking runway".
The Snow Dragon's escape means that the Shokalskiy now remains trapped in the ice alone. But the Polar Star, a US Coast Guard icebreaker that had been dispatched to come to the aid of the trapped ships, is expected to arrive on Sunday.
The vessel, which is cutting short a stop in Australia, is capable of breaking 2m of ice continuously and a maximum of 6.5m by backing up and ramming it, according to the US Coast Guard.