SYDNEY (AP) — A conservationist group that lost one of its ships in a clash with Japanese whalers off Antarctica has filed a piracy complaint in the Netherlands against the captain and crew of the whaling vessel, one of the group's leaders said Saturday.

The filing comes after the bow of the Sea Shepherd Conservation Society's Ady Gil was sheared off in a collision Wednesday with the far larger Japanese ship — the most serious clash in what has become an annual confrontation off the frozen continent. A Sea Shepherd volunteer suffered cracked ribs.

The whaler, Shonan Maru No. 2, suffered no apparent damage. Both sides blame the other for the crash, which occurred as the Ady Gil harassed the Japanese fleet. On Friday, Sea Shepherd lodged a piracy complaint with the Dutch prosecuting authority, Sea Shepherd Deputy CEO Chuck Swift told The Associated Press by satellite phone from his ship, the Bob Barker.

The ship is named for the former TV game show host, who donated $5 million to buy it.

A copy of the complaint translated from Dutch to English by Sea Shepherd officials was provided to the AP. It argues the whalers are guilty of piracy because they served on a vessel that was used to commit an act of violence. The complaint urges Dutch authorities to take action within two weeks.

"They have certainly proven that some of them have as much disregard for the law and human life as they do for the law and whale life," Swift said. "We could have had six dead."

The group chose to file the complaint in the Netherlands because one of the Ady Gil crew members is Dutch and the Sea Shepherd's main ship, the Steve Irwin, is registered there, according to the complaint.

Sea Shepherd is also considering filing charges of attempted murder in New Zealand, where the Ady Gil was registered, Swift said.

Glenn Inwood, the New Zealand-based spokesman for Japan's Institute of Cetacean Research, which oversees the whaling fleet, dismissed the filing as a publicity stunt.

"They have no real basis here for filing any claims at all, especially of piracy," Inwood told the AP. "The chances of them winning anything, the odds are well against it — noting that they were in the wrong for the incidents to start with."

Given the circumstances, a piracy charge would be difficult to prosecute, said Don Rothwell, a professor of international law at the Australian National University who wrote a recent report for the government on Antarctic whaling.

An act of piracy usually requires that a vessel be boarded or seized, that goods be taken from the vessel or that a person is held on the vessel, he said.

While Sea Shepherd could claim that an act of violence justifies a charge of piracy, such a charge requires that the act of violence occurred for private means, Rothwell said.

The whaling fleet would likely be considered public vessels under government control, he said.

Japan kills about 1,200 whales a year in Antarctica under what it says is a scientific programme allowed by the International Whaling Commission, despite a moratorium on commercial whaling.

Critics say the program is a front for illegal whaling, and Sea Shepherd sends ships to Antarctica each season to try to stop the hunt — an effort portrayed on the Animal Planet TV series "Whale Wars".

After Wednesday's clash, the Bob Barker began towing the Ady Gil toward French research base Dumont d'Urville, 185 miles to the south.

But the tow rope snapped en route, so the Ady Gil was left to sink and the Bob Barker resumed its pursuit of the Japanese whalers, said the Bob Barker's first officer, Peter Hammarsedt. Australian Environment Minister Peter Garrett on Friday ramped up pressure on Japan to end whaling by threatening legal action if diplomatic efforts do not show results before the next International Whaling Commission summit in June.