Tokyo plans to hand over to Australia three anti-whaling activists held aboard a ship escorting the Japanese harpoon fleet on an Antarctic hunt, Japan\'s Jiji Press news agency reported Monday. Japanese government officials told Jiji that the authorities had no plans to file criminal charges against the three Australians. The men from the Forest Rescue Australia environmental group boarded the Shonan Maru No.2 around 16 miles (26 kilometres) off Australia\'s west coast on Saturday night. Forest Rescue said it wanted to stop the Shonan Maru tailing the Steve Irwin, a ship from anti-whaling group Sea Shepherd, back to the Southern Ocean, where Japan annually hunts for whales. It is not the first time an activist has boarded the Shonan Maru No.2 -- New Zealander Pete Bethune was arrested and taken back to Japan to be tried after sneaking on to the ship during the heated 2009-2010 anti-whaling campaign. He spent five months in prison and was handed a two-year suspended sentence. The latest incident was less serious because no Japanese crew members had been injured, the Japanese officials told Jiji. Australian Attorney-General Nicola Roxon earlier Monday said Canberra was \"in diplomatic discussions\" with Tokyo to seek the release of the three men. Sea Shepherd claimed the men were \"being held as prisoners\" on board the Shonan Maru, which has been tracking the Steve Irwin. The Steve Irwin returned to Australia last week because another Sea Shepherd ship, the Brigitte Bardot, was damaged in high seas and needed escorting home, setting back the group\'s annual harassment of the whalers. Japanese whaling spokesman Glen Inwood, from the Institute of Cetacean Research, said the men were being treated well. \"The Australians are being very compliant. They haven\'t offered any resistance,\" he told ABC radio. Tokyo has urged Australia to do more to prevent disruption to its whaling fleets following the latest incident. The Japanese foreign ministry made the request to the Australian embassy on Sunday, hours after the trio boarded the Shonan Maru, an official at the ministry\'s fishery division said. \"We told the embassy that we regretted such an obstructive activity and asked for efforts on Australia\'s part to prevent it from recurring,\" the official said. Three whaling ships, led by the 720-tonne Yushin Maru, left the Japanese port of Shimonoseki on December 6 for the annual hunt, with security measures beefed up amid simmering international protests. In previous years, a mother ship has joined them later. Commercial whaling is banned under an international treaty but Japan has since 1987 used a loophole to carry out \"lethal research\" on the creatures in the name of science.