Japan has sent a giant military icebreaker to bolster its whaling fleet in the conflict with Sea Shepherd in the Southern Ocian, anti-whaling activists say.
The 12,500 tonne Shirase, operated by the Japan Maritime Self-Defence Force, has appeared near whalers and Sea Shepherd, the group said.
The ship was recognised on radar by its identification signal, according to Sea Shepherd.
The Korean tanker Sun Laurel was making a renewed attempt to refuel the whalers' factory ship Nisshin Maru under the shelter of a Coast Guard helicopter from Shirase, Sea Shepherd's Paul Watson said.
The powerful icebreaker can carry up to 250 crew and three helicopters, and has conducted Antarctic resupply duties for Japan, according to the Japanese Ministry of Defence website.
Shirase was scheduled to be in the region conducting Antarctic scientific work off nearby Cape Darnley, an informed Australian source said.
The ship was due to be working on ocean moorings, which are used to collect oceanographic data.
The Japanese Government had no immediate comment on the Shirase's use, or the presence of the helicopter over the Sun Laurel.
Sea Shepherd Australia director Bob Brown said the Shirase's last know port was Fremantle and last position received was 86 days ago.
''So I guess it has been out at sea for a while,'' he said. ''It may not be here for us specifically but is likely getting involved now.''
A blockade by Sea Shepherd stopped the Nisshin Maru from reaching the tanker last week.
Instead the whalers' mother ship was involved in a series of dramatic collisions with the Sun Laurel, and three Sea Shepherd vessels.
According to Watson, after spending several days north of the ice, the Sun Laurel turned south, and early on Monday was approaching Nisshin Maru.
The ships were about off Mackenzie bay, far south-west of Perth, in a wildlife-rich area of Antarctica near the Amery Ice Shelf.
The Japanese government has repeatedly called for Sea Shepherd to end its obstruction of the whaling fleet.
It said the activists endangered the lives of the crew, and property, and safe navigation at sea.
- Sydney Morning Herald