Sea Shepherd, the anti-whaling activist group, has released video of one of its ships being "rammed" by a Japanese harpoon ship, in what the organisation called an "unprovoked attack".
No one was injured, though both ships received minor damage in the Sunday's collision - the latest drama in an annual battle between the conservationists and the whalers. Both sides are blaming each other for the crash.
The group said one of its vessels was the victim of a co-ordinated attack by three Japanese ships, to keep activists away from its factory ship Nisshin Maru.
In a statement, Sea Shepherd said: "The Bob Barker was hit by the Japanese whaling fleet's harpoon vessel, the Yushin Maru No 2, as the harpoon vessel crossed in front of the bow of the Sea Shepherd ship.
"The assault is an attempt to deter the Sea Shepherd ships from their current position, blocking the slipway of the Nisshin Maru, preventing the whalers from loading whales poached from the southern ocean whale sanctuary."
The group called it a "calculated midnight ambush, aimed to oust the Sea Shepherd ships from non-violently blocking the slipway of the Nisshin Maru."
"These harpoon ships came in heavy and hard. They hit my bow with about 300 metres of steel cable with the express intent of causing damage to my rudder and propellers," Captain Peter Hammarstedt told the Australian ABC.
"Certainly the whalers were more aggressive than we have ever seen them before and I think we're quite lucky that nobody was hurt".