Tokyo ( CNN ) -- Three Australian activists are being held aboard a Japanese ship Monday after illegally boarding the vessel to protest Japan 's annual whale hunt in Antarctic waters . The three men are not yet under arrest , but are being questioned by Japan 's Coast Guard , a spokesman for Japan 's Fisheries Agency said Monday , declining to be identified as is customary in Japan . The Australian attorney-general , Nicola Roxon , said that her government was working to secure the release of the men , but that she believed they could face criminal charges in Japan . Video footage released by the anti-whaling group Sea Shepherd shows the three men , from the environmental group Forest Rescue Australia , approaching the Japanese vessel on a small boat on Sunday . The video shows their boat pull up next to Japan 's Shonan Maru # 2 , a patrol vessel supporting Japan 's whaling mission in the Antarctic waters . A voice from the small boat calls out , `` Go , go , go ! '' as the men slip onto the Japanese ship . In the background , voices in Japanese scream in alarm , saying `` They 're boarding ! '' Sea Shepherd described the three activists -- Geoffrey Owen Tuxworth , 47 , Simon Peterffy , 44 , and Glen Pendlebury , 27 -- as `` prisoners . '' The organization said the men boarded the vessel to force Japan 's fleet to stop hunting whales . Japan annually hunts whales despite a worldwide moratorium , utilizing a loophole in the law that allows for killing the mammals for scientific research . Each year , environmental groups like Sea Shepherd face off with Japan 's hunters in a high seas drama that has led to collisions of ships , the detaining of activists and smoke bombs fired back and forth between the groups . Two days before he boarded the Japanese vessel , Peterffy said in a video released by Sea Shepherd that stopping Japan 's hunts was a personal responsibility . `` We 've got a big responsibility for all those people in future generations , '' he said . Australia 's Roxon said the countries were engaged in diplomatic discussions to ensure the well-being and safety of the three men , but called it a `` difficult situation . '' Roxon said that while Australia steadfastly opposes Japan 's whale hunt , the incident did not happen in Australian territorial waters . `` That does n't give us rights for Australian law to automatically apply , '' she said . `` In fact , our advice is that Japanese law will apply because a Japanese boat is the one that 's been boarded . '' This is the third time activists have boarded ships involved in the Japanese whaling fleet . In 2008 , two Sea Shepherd activists sneaked aboard a Japanese vessel . They were released back to the anti-whaling group . In 2010 , Pete Bethune , a New Zealander , also boarded the Shonan Maru # 2 . Bethune was arrested , taken back to Japan , and tried in a Tokyo court . He spent five months in prison and was released on a two-year suspended sentence .
The three activists could face criminal charges in Japan , an Australian official says . Score: 6 The Australian government is working to secure the activists ' release . Environmental groups have clashed in previous years with the the whale-hunting vessels .