The battle between Sea Shepherd activists and whalers appears to be reigniting with more collisions in the Southern Ocean and the arrival of a Japanese military-style ship.
The conservation group says the factory ship Nisshin Maru rammed Sea Shepherd's vessel Bob Barker twice on Monday afternoon, causing it to collide with the tanker Sun Laurel.
Sea Shepherd says "a flash bang grenade" has been thrown by the whalers.
The group says it was attempting to block a refuelling operation in the Australian Antarctic Territory, the same action that sparked a dangerous confrontation last week.
Sea Shepherd says a Japanese military icebreaker, the Shirase, has arrived to assist the whalers reports AAP.
Sea Shepherd says two of its ships, the Steve Irwin and Sam Simon, have had their engine rooms flooded by water cannons and it has responded in kind.
The 12,500-tonne Shirase, which can carry 250 people and three helicopters, is operated by the Japan Maritime Self Defence Force tasked with the naval defence of the country.
Federal environment minister Tony Burke issued a please-explain to Japan about the ship's role, suggesting it was exploiting a loophole by assisting the Korean tanker rather than the Japanese whalers directly.