An Australian icebreaker carrying 52 passengers rescued from a Russian ship stuck in frozen Antarctic waters on Thursday has been told to halt its journey home after a Chinese vessel involved in the operation said it, too, may be unable to move because of heavy ice.

The Australian Maritime Safety Authority (AMSA) said the Xue Long - or Snow Dragon - had signalled that it " has concerns about their ability to move through heavy ice in the area." AMSA said the Australian ship, the Aurora Australis, had been told to "remain in open water in the area as a precautionary measure."

AMSA said the Chinese ship would try to maneuver through the ice when tidal conditions are most suitable during the early hours of Saturday. It said those on board were not in any immediate danger.

The Xue Long provided the helicopter used in the retrieval of the passengers stuck on the Russian research ship Akademik Shokalskiy, and has not moved for several days while taking part in a number of rescue attempts.

Dramatic airlift

The Akademik Shokalskiy became stuck in frozen seas on Christmas Eve, 100 nautical miles (185.2 km) from the French base Dumont d'Urville. The helicopter was finally used to transfer its passengers to the Aurora Australis after both the Xue Long and the Aurora Australis had tried unsuccessfully to break through ice to reach the stricken vessel.

Plans for the helicopter rescue were initially delayed by extreme weather conditions.

The Aurora Australis had been making for an Australian base on its way to Hobart, the capital of Australia's island state of Tasmania, when it was told to stand by.

The Akademik Shokalskiy remains stuck in the ice with 22 Russian crew on board. AMSA said the vessel would try to free itself when circumstances permitted - which could be in several weeks' time.

Its passengers had beeen following in the footsteps of Australian explorer Douglas Mawson and his 1911-1914 expedition.

The costs of the rescue will be shared by the owners of the ships and their insurers in accordance with international conventions on sea rescues, according to ASMA Emergency Response Division manager John Young.

tj/pfd (AFP, AP)