Sydney - Environmental activist group Sea Shepherd admitted on Monday it was struggling to find Japanese whaling vessels in the vast Southern Ocean and urged the Australian government to help.
Its flagship Steve Irwin left Western Australia for the remote area on January 18 to chase and disrupt the annual hunt, which resumed in December after a one-year pause despite a worldwide moratorium and widespread condemnation.
After a decade of harassment by Sea Shepherd, Japan was forced to abandon its 2014-15 hunt after the International Court of Justice said the expedition was a commercial activity masquerading as research.
Tokyo maintains it is trying to prove the whale population is large enough to sustain a return to commercial hunting, and says it has to kill the mammals to carry out its "scientific research" properly.
"The Japanese whaling fleet has greatly expanded their area of illegal operations in the Southern Ocean. This makes finding them very difficult," said Sea Shepherd founder Paul Watson.
Australia, which has led global efforts to persuade Japan to halt whaling, has previously floated the idea of sending a customs vessel to monitor the hunt in the Southern Ocean, but it appears not to have followed through.
"Sea Shepherd was expecting that Australia or New Zealand would uphold their obligations as responsible members of the International Whaling Commission, to send a ship to intercept the Japanese whaling fleet," said Watson.
"This does not seem to be something Australia or New Zealand are willing to do."
He called on Canberra to provide Sea Shepherd with the exact coordinates of the whaling fleet "so that Sea Shepherd can do the job that Australia and New Zealand refuse to do".
"If Australia or New Zealand can kindly provide the coordinates, Sea Shepherd can stop the continuing illegal operations of the renegade outlaw Japanese whaling fleet."
Environment Minister Greg Hunt was non-committal on Monday when asked if the government would send a ship or provide coordinates.
"We do not accept in any way, shape or form the concept of killing whales for so-called 'scientific research'," his spokesperson told AFP.
"We will continue to urge Japan to pursue non-lethal methods of research and end its unnecessary whaling programme.
"Australia is committed to the protection of whales and we will continue to work with the international community to promote whale conservation and uphold the global moratorium on commercial whaling."