The Australian government is in diplomatic talks with Japan to secure the release of three anti-whaling activists who are presently held on board a Japanese ship, Shonan Maru II, which they boarded around 16 miles off Australia's west coast on Saturday night.

However, Australian Attorney-General Nicola Roxon conceded the three, Geoff Tuxworth, 47, Simon Peterffy, 44, and Glen Pendlebury, 27, are likely to suffer the consequences of taking the law into their own hands.

Roxon said that while the federal government was doing all it could to assist the men, who are members of Forest Rescue Australia, the probability is that they would be dealt with under Japanese law.

"We are doing all we can diplomatically to ensure that these three Australian men can be released quickly and properly and to make sure that they are being held in conditions that are appropriate," Roxon told the ABC.

A spokesman for the Japanese whaling program at the Institute of Cetacean Research, said the incident occurred about 25 miles (40km) off the West Australian coast, outside Australian territorial waters but inside Australia's 200-mile (320km) economic zone.

According to Australian government's website, the government's contiguous zone is adjacent to its territorial sea, extending up to 24 nautical miles from its territorial sea baseline. In this zone, Australia "may exercise the control necessary to prevent or punish infringements of its customs, fiscal, immigration or sanitary laws and regulations."

Meanwhile, Australia's "exclusive economic zone extends from the outer edge of the territorial sea up to 200 nautical miles from the territorial sea baseline. The outer limit is less than 200 nautical miles in some areas, in accordance with agreements with neighbouring countries."

In its exclusive economic zone, Australia has sovereign rights to "explore and exploit, conserve and manage the natural resources of the waters, seabed and subsoil. Jurisdiction also extends to the establishment and use of artificial islands, installations and structures, marine scientific research, the protection and preservation of the marine environment, and other rights and duties."

Forest Rescue has demanded that the activists be returned to Australia, saying that the activists boarded the Shonan Maru to prevent it from tailing the Steve Irwin, a ship from anti-whaling group Sea Shepherd.

According to Roxon, it was difficult because the incident didn't happen in Australia's territorial waters. "Because it was only in our exclusive economic zone, that doesn't give us automatic rights to assert Australian law," she was quoted to say.

However, Sea Shepherd's leader, Paul Watson, said the three men had boarded the Japanese vessel within Australia's 24-mile contiguous zone, in which Australian laws apply.

The Australian Attorney-General said that while the government did not welcome the presence of the Shonan Maru No 2 in Australia's exclusive economic zone, they need to act within the law.

"We are considering all options. Our top priority is to ensure these three Australian men are being treated properly and to arrange for their return to Australia as quickly as possible," Roxon said.

She emphasized that steps to prevent whaling will continue, including taking action in the International Court of Justice.