The Sea Shepherd Conservation Society claims new footage clearly proves its high speed anti-whaling protest boat was deliberately targeted by a Japanese whaling ship in Antarctic waters.
It says footage from aboard the protest boat shows the Japanese vessel altered its course to head into the path of the Ady Gil, and ram it.
The society has asked a public prosecutor in the Netherlands to hold a criminal investigation into the collision on Wednesday. The Ady Gil sank while under tow on Friday morning.
However, the Institute of Cetacean Research says Sea Shepherd's footage is inconclusive.
Spokesman Glenn Inwood says its footage shows the Ady Gil was powering up and moving forward in the direction of the Shonan Maru Number Two.
He says Japan has never deliberately rammed any boat in the Antarctic.