A United States Coast Guard icebreaker will help to free two ships stuck in ice in Commonwealth Bay in the Antarctic.
The Polar Star is bound for Antarctica for a month to clear a channel to McMurdo Sound so supply ships can take food, fuel and other goods to the research station.
The Australian Maritime Safety Authority has asked the US icebreaker to help the Russian ship Akademik Shokalskiy and the Chinese ship Xue Long (Snow Dragon) which is also now stuck.
Twenty-two crew remain on board Akademik Shokalskiy, which sparked a rescue mission after a blizzard pushed sea ice around the ship and froze it in place on Christmas Eve, the 52 scientists and tourists on board the research ship were airlifted to safety last week.
The Polar Star will leave Sydney on Sunday after taking on supplies for its voyage to Antarctica. AMSA said it will delay this work and is expected to take a week to reach the two ships.
The Polar Star is one of the largest ships in the US Coast Guard fleet. It is based at Seattle with 140 crew.
AMSA said the Polar Star had greater capabilities than the Russian and Chinese vessels.
"It can break ice over six metres thick, while those vessels can break one-metre ice," a spokeswoman told AAP.