A whaling catch: campaigners try to stop this happening.

Conservationists aboard three ships are hoping to track down the whalers.

The activists have threatened to ram the Japanese ships and force them back to port.

Others intend to use small inflatable boats to put themselves between the hunters and their prey.

Finding the fleet in such a vast area is difficult, so the campaigners have offered a reward for anyone who can help.

"The Japanese are reported to be using satellites to keep one step ahead of their pursuers", said BBC correspondent Phil Mercer who's monitoring the story from Sydney.

"The New Zealand air force filmed the whaling fleet last week but is refusing to divulge any details of its location because of the threat of confrontation".

New Zealand and Australia both oppose Japan's whaling programme.

Divisions

The Japanese expedition could deepen divisions ahead of a controversial meeting of members of the International Whaling Commission in Japan next month.

It is likely that only the pro-whaling members of the IWC will attend that meeting - reports suggest that several countries opposed to the practice may boycott the assembly.

St Kitts & Nevis, one of the IWC members which supports Japan's campaign for the lifting of the temporary ban, and their Fisheries Minister Cedric Liburd told BBC Caribbean that they intended to be present.

"When you look at the issues and the decisions that are taken at IWC, it (the IWC) has to be reviewed," Mr Liburd told BBC Caribbean.

"Every country goes there trying to separate themselves from another and so forth and it is not good for the future of the IWC."

Observers say the absence of anti-whaling nations from next month's meeting could leave the future of the world body in doubt.

	Japan is counting on the support of Caribbean and other pro-whaling nations

Arguments

Last year, pro-hunting nations gained their first IWC majority for 20 years.

The British government will publish a brochure this coming week aimed at encouraging nations opposed to whaling to join the Commission.

It says whales are "sensitive, social creatures", with some species risking extinction. Japan says these arguments are "old rhetoric and half-truths".

Japan, Iceland and Norway, the principal pro-whaling nations, believe that many stocks are large enough that hunting can be sustainable.

They dismiss arguments that whales are special and distinct creatures as being relevant only in certain cultures.