AUSTRALIA plans to spy on the Japanese whaling fleet using an armed P&O cruise ship, with a lesser role for the Australian Defence Force.

High-level talks have focused on leasing the commercial vessel, Oceanic Viking, which has a re-enforced hull to cut through ice, a crew trained for polar conditions and "super-telephoto" lenses to record the whale slaughter.

Sources said the ship would also carry video equipment, and the images would be used in Australian international court action planned against the Japanese whale hunt, the largest for 20 years. The images would complement a series of aerial surveys on whale populations, to begin soon.

Under plans being developed, the Oceanic Viking would have two .50-calibre machine-guns manned by a customs boarding party to supply the "muscle", while working with a civilian P&O crew. It is highly unlikely the guns would be fired or Japanese ships boarded. The 105-metre vessel has already been used to chase foreign poachers of the Patagonian toothfish in the Southern Ocean.

"The bottom line is you have got to get close to really see what is going on," one source said. Satellite technology would be of limited use against whalers and unmanned aerial vehicles would be unlikely to have sufficient range. The imminent Japanese Government-backed hunt aims to slaughter 935 minke whales and 50 fin whales. For the first time since 1963, humpbacks - 50 of them - are being targeted.