Ady Gil collision inquiry 'inconclusive'

Ady Gil collides with Shonan Maru 2 in January. Photo / Supplied

MELBOURNE - Australian maritime authorities have been unable to conclude who caused the collision between a Japanese whaling ship and a speedboat carrying protesters during heated clashes in the Antarctic.

The anti-whaling trimaran Ady Gil, part of the Sea Shepherd fleet, and the Shonan Maru 2 collided in remote Antarctic waters on January 6, slicing the high-tech protest boat in half.

New Zealand authorities are also investigating the collision.

An investigation into the incident by the Australian Maritime Safety Authority (AMSA), released this week, failed to find which party was to blame after the Japanese government refused to co-operate and video footage proved inconclusive.

Japan's government declined to participate in the investigation, saying any information it had might be needed for an inquiry by its own authorities.

"On the basis of the available evidence, AMSA has been unable to determine whether either vessel took any action intended to cause a collision," the report said.

"(Due to) the lack of access to the crew and the absence of a detailed response from the Shonan Maru No.2, AMSA was unable to collect sufficient evidence to fully examine the circumstances pertaining to compliance with regulations or to conclude the facts of the matter."

Sea Shepherd Captain Paul Watson claimed the whaling ship had turned at the last minute and headed directly for the Ady Gil, ripping a three metre section of the bow and sinking it in the Southern Ocean.

But Japanese authorities blamed the protesters, saying the Ady Gil slowed suddenly while crossing in front of the Shonan Maru.

AMSA said it had been unable to verify the claims of the Sea Shepherd crew with other witnesses.

The report said the crews of both vessels had been warned about the dangers of collisions before the whaling season began.

"AMSA also communicated its concerns, including concerns about the durability of the Ady Gil in the event of a collision, directly to the master and crew," the report said.

The Japan Coast Guard is considering launching a criminal case over allegations of sabotage by the Sea Shepherd crew, the report said.

The Australian Federal Police is conducting a separate investigation into the claims - including the alleged throwing of rancid acid at the whaling ship - at the request of the Japanese government.

Australian Greens Leader Senator Bob Brown labelled the report a "political cop out" and called on Australian authorities to prosecute the captain and crew of Shonan Maru 2.

"Australia, which had the last port of call for the Ady Gil, has unfettered ability to pursue the captain of the Japanese whaler Shonan Maru 2 which ran down the Ady Gil and nearly killed the six crew aboard," Senator Brown said in a statement.

- AAP