Mr Watson is wanted by Japan over his Antarctic anti-whaling campaigns, and after skipping bail in Germany has been at sea for months to avoid arrest.

The former Greens leader Bob Brown said on Monday a key job in his new role as a Sea Shepherd Australia director was to ensure that Mr Watson could come ashore safely, and warned an arrest would bring uproar.

Mr Watson, who is on board the ship Steve Irwin in the Southern Ocean, said he had been given a business entry visa to Australia by the Australian Embassy in Washington.

''But I don't have a passport,'' Mr Watson said. ''Both my Canadian and US passports are in Germany.''

A repeated visitor to Australia on his campaigns, Mr Watson said his group had decided to base their international operations at Williamstown in Melbourne, and it made sense for him to be able to come ashore.

''It would be nice to come ashore anywhere, really,'' he said.

Interpol has Red Notices from Japan and Costa Rica outstanding for Mr Watson.

According to the global policing organisation, a Red Notice is a request for any country to locate an individual with a view to their provisional arrest and extradition, in accordance with that country's national laws.

Dr Brown said there was no requirement for Australia to arrest Mr Watson if he set foot in Australia.

''No, not at all,'' Dr Brown said. ''The red alert is simply that. It's an alert. I would think that if Paul Watson were to be arrested at some future time, there'd be uproar in Australia.

''What Australia should be doing is arresting the captains of the Japanese whaling fleet who are illegally down there harpooning whales in an international whale sanctuary.''

Environment Minister Tony Burke said at the weekend that if Mr Watson came to Australia there would be no intervention from the government.

''You'd have a situation where various agencies would do their job,'' Mr Burke said

Japan's Institute for Cetacean Research obtained an interim injunction from a US Appeals Court restraining Sea Shepherd vessels from attacking the whalers this season.

It has called on Australia, as a Sea Shepherd flag state, to act against the group.

The Japanese consul-general in Melbourne, Hidenobu Sobashima, said his government was concerned about Sea Shepherd jeopardising the safety of crews and property.

''Generally speaking we believe those people responsible for those actions should be dealt with properly,'' Mr Sobashima said.

The whaling fleet only left Japan last Friday, losing weeks of its Antarctic season after a partial refit of the factory ship, Nisshin Maru.

It is believed to be a four-ship fleet - meaning Sea Shepherd would match its numbers.

With the Steve Irwin at sea, the Bob Barker and Brigitte Bardot are expected to leave Wellington, New Zealand, soon. The group's fourth ship, Sam Simon, is likely to depart Hobart within a week.