BBC-An Australian vessel is en route to East Antarctica in a renewed bid to free a scientific mission ship trapped in dense pack ice since Tuesday.

Earlier rescue attempts by Chinese and French icebreakers were foiled by the thick ice.

However, a BBC correspondent on the Russian research vessel says big cracks have appeared, raising hopes that it may even be able to move on its own.

Seventy-four scientists, tourists and crew are on the Academician Shokalskiy.

The vessel is being used by the Australasian Antarctic Expedition to follow the route explorer Douglas Mawson travelled a century ago.

The Shokalskiy remains well stocked with food and is in no danger, according to the team.

Despite being trapped, the scientists have continued their experiments, measuring temperature and salinity through cracks in the surrounding ice.

Unpredictable weather

The Australian Maritime Safety Authority (AMSA), which is coordinating the rescue, said the Aurora Australis was expected to reach the trapped research ship on Sunday around 12:00 GMT.

The powerful icebreaker can cut ice up to 1.6m (5.2ft) thick - potentially still enough to plough through the estimated three-metre wall surrounding the Shokalskiy.

If this latest relief operation fails, passengers could be winched to safety by a helicopter on board the Chinese icebreaker, which had to abort its rescue mission on Saturday.

The Snow Dragon came within seven nautical miles (11 km) of the Russian ship before stalling and being forced to return to the open sea.

The BBC’s Andrew Luck-Baker, who is part of the expedition, said the helicopter flew around the Shokalskiy on Sunday to see if the Snow Dragon could launch another attempt to break through the ice.

Our correspondent says a change in wind direction and slightly warmer temperatures have caused the ice to break and formed pools of water.

But he also warns that conditions could worsen again because of the Antarctica’s extremely unpredictable weather.