Wellington, March 26 NZPA - The New Zealand Government has a duty to investigate the clashes between conservationists and whalers in the Southern Ocean as one of the vessels involved in the clashes is NZ flagged, says a European academic.

Professor Fred Soons of the Utretcht University School of Laws told the Wellington-based LawFuel legal news website that the Dutch government was also obliged to investigate as the Sea Shepherd Conservation Society vessel Steve Irwin was a Netherlands ship, and similarly the Japanese government with Japanese-flagged vessels.

Maritime NZ confirmed today that the Ady Gil trimaran allegedly rammed and sunk by a Japanese ship was flagged to this country.

If either the Japanese or the conservationists had deliberately rammed each other, they would have violated law on the safety of navigation, said Prof Soons.

Under international law, such acts could also be criminal acts under the Convention on the Suppression of Unlawful Acts Against the Safety of Maritime Navigation.

"If they can be considered to have been conducted 'for private ends' ... they constitute also piracy."

Prof Soons -- who has served with the Dutch Navy -- visited Auckland to lecture on the resurgence of maritime piracy. He teaches on the International Law of the Sea at Utrecht University in the Netherlands. He is the director of the Netherlands Institute for the Law of the Sea and works on boundary disputes between nations.

Professor Soons said that a new interest in the law relating to piracy had been triggered by the situation off the coast of Somalia, where several hundred million dollars had now been paid in ransoms to obtain the release of ships seized by pirates.