The Australian government says it is doing everything it can to try to ensure the release of three anti-whaling activists being held aboard a Japanese surveillance boat.
The Sea Shepherd Conservation Society helped the three from an environmental group called Forest Rescue sneak on board the Shonan Maru 2 off the coast of Western Australia on Saturday night.
The Shonan Maru 2 is used to tail anti-whaling ships and is currently pursuing Sea Shepherd's ship, the Steve Irwin.
The ABC reports Simon Peterffy, 44, Geoffrey Tuxworth, 47 and Glen Pendlebury, 27, boarded the vessel in the hope that it would be forced to return them to shore and abandon shadowing the Steve Irwin.
However, this has not been the case.
Attorney-General Nicola Roxon says it is possible the men will be taken to Japan, where they could face penalties under Japanese law.
The ABC reports whaling boats are banned from docking at Australian ports.
The Institute of Cetacean Research has confirmed the three are on the Japanese boat.
Spokesman Glenn Inwood said the men were being questioned. He said the Shonan Maru 2 was 40km off the Australian coast when they boarded it.
The Shonan Maru 2 was previously boarded during the 2009-2010 campaign season by Pete Bethune of New Zealand who was taken back to Japan, where he was given a two-year suspended prison sentence.