The IWC's 72 members are bitterly divided over a 25-year-old global moratorium on whaling which Japan and other nations such as Norway oppose.

Japan has long resisted pressure to stop scientific whaling and this year plans to hunt 935 minke and for the first time 50 humpbacks. Humpbacks were hunted nearly to extinction until protected by the IWC in 1966.

Tokyo has been accused of doling out US$750 million in aid to small Caribbean and Pacific countries to gather support in the IWC for overturning the 1986 ban on all whaling.

Japan last year succeeded in gaining a majority of IWC votes, but not the 75 percent needed to resume commercial whaling.

Michael McIntyre, IFAW's Asia Pacific Director, said conservationists wanted an anti-whaling nation such as Australia or New Zealand to take legal action against Japan. Belgium was also sympathetic, he told Reuters.

Rothwell, an international law specialist at the Australian National University, said he was confident Japan's fast-expanding whaling programme could be stopped through the International Tribunal for the Law or even the International Court of Justice.

"There are a range of legal options that would be available," he told Australian radio, citing a report prepared by law experts from the United States, France, Australia and Mexico.

Japan this year invited IWC members to Tokyo to talk about an end to the moratorium. Around 26 anti-whaling countries, including New Zealand, Australia, the United Kingdom, the United States and Argentina boycotted the meeting.

Japan says whaling is a cherished cultural tradition and began scientific research whaling in 1987.