A shipping expert who has viewed video footage of a collision between a Sea Shepherd vessel and a Japanese harpoon boat over the past weekend says the encounter was probably unintentional.
Anti-whaling group Sea Shepherd and Japan's Institute of Cetacean Research have both released videos of the collision. Both groups say the footage clearly show the other side deliberately ramming them.
Watch the video released by Sea Shepherd
Watch the videos released by the Institute of Cetacean Research in Tokyo
But Wellington-based marine risk consultant John Riding from Marico Marine has analysed the videos and says the collision is a classic example of what's known as 'interaction'.
"When two ships are moving through the water together, the water passing between the vessels has to go faster so the two hulls get pulled together. And you can see the bow of the Sea Shepherd vessel is actually sucked in towards the Japanese vessel, and I'd be quite confident to say that it wasn't an intentional collision."
The release of the videos came after Sea Shepherd accused three Japanese harpoon vessels of launching a protracted attack against vessels Steve Irwin and Bob Barker in the Southern Whale Sanctuary on Saturday, with one hitting the bow of the Bob Barker.
But Japan's Institute of Cetacean Research spokesperson Glenn Inwood told Radio New Zealand's Morning Report programme on Monday the video of the incident showed a Sea Shepherd ship steering into a Japanese vessel.
"Yesterday when Sea Shepherd released that video, all of that footage of what they said occurred in the Southern Ocean, I said to your reporter that it seriously needed to be questioned, and the release of the unedited footage from the Japanese government overnight clearly demonstrates the falseness of that group's claims."
Bob Parker captain Peter Hammarstedt was adamant Sea Shepherd ships had been attacked. He told Morning Report on Monday he believed the attacks were premeditated, unprovoked and completely ruthless.
"Three of the Japanese harpoon vessels belonging to the Japanese whale-poaching fleet came in and deliberately attacked the Steve Irwin and the Bob Barker...the two Sea Shepherd ships....It was completely ruthless. These three harpoon vessels were towing over three hundred metres of steel cable. They crossed my bow a total of 41 times in an effort to deliberately damage my rudder and my propeller."
Australian Environment Minister Greg Hunt has ordered an investigation into the collision. He said that should send a message to both sides that nobody can play games with safety in the dangerous waters of the Southern Ocean.