A JAPANESE whaling security ship carrying three Australian activists was last night heading into the Southern Ocean, despite diplomatic efforts to retrieve them.

The Shonan Maru No.2 kept up its pursuit of the Sea Shepherd ship, Steve Irwin, as the federal government sought to resolve the crisis sparked by the three's boarding.

With the government yet to obtain consular access to the men, their supporters in Perth said they were scheduled to begin a hunger strike. The government was resisting Coalition and Greens pressure to send a Customs patrol ship south to monitor the whaling conflict.

The Attorney-General, Nicola Roxon, called for ''cool heads'' to prevail as the government sought to ensure the return of the men to Australia.

The boarding fuelled debate about the use of the government's Southern Ocean patrol ship, the Ocean Protector, which was docked in Fremantle on Friday when the Steve Irwin called to refuel.

The Opposition Leader, Tony Abbott, said the vessel should be sent to keep the peace over whaling. ''The best way for Australia to exercise some influence and to do good in the Southern Ocean would be to put an Australian Customs vessel down there so that as far as is humanly possible, we can keep the peace in the Southern Ocean during the whaling season,'' Mr Abbott said.

The Greens leader, Bob Brown, said he would introduce legislation to require an Australian patrol ship to be on station whenever whaling occurred in an Australian whale sanctuary.

This season the Japanese fleet is expected to take up to 930 minke whales and 50 fin whales under a self-awarded scientific whaling permit. It is slated to operate mainly in waters declared a whale sanctuary off the Australian Antarctic Territory.

Ms Roxon poured cold water on the prospect of sending the Ocean Protector south, describing it as ''macho chest-beating''.

Experienced anti-whaling activists told the Herald they doubted that the Shonan Maru No.2 would break off its pursuit of the Steve Irwin to return the activists to Australia.