Anti-whaling group Sea Shepherd says a Japanese whaling ship has rammed its two protest ships, and one has taken on water.
Sea Shepherd founder Captain Paul Watson, in a posting on his Facebook page on Wednesday afternoon, claimed the Nisshin Maru had rammed both the Steve Irwin and the Bob Barker, "but both vessels continue to hold their positions.
The Bob Barker is taking on water in their engine room."
They are in the Southern Ocean, north of the Australian Casey Research Station. Speaking from aboard the Steve Irwin, Watson told 3 News the Bob Barker, with 38 crew aboard, was hit a number of times as they tried to stop the Nisshin Maru from refuelling, which he says is illegal in the Southern Ocean.
"(It) has lost power, toppled the main mast, smashed up the deck."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
A mayday has been issued but the crew had managed to stop water from coming in, he said.
The Australian Maritime Safety Authority is responsible for responding to maydays in that part of the ocean.
The authority is in the process of responding. Capt Watson said the Japanese ship had also struck the Korean-owned fuel tanker, the Sun Laurel.
The Japanese Institute of Cetacean Research could not be reached for immediate comment, but last week it said the Bob Barker had tried to sabotage Japanese research vessel Nisshin Maru and Yushin Maru No.2 as they tried to transfer a whale between the two ships.
The confrontation comes the same month the US Supreme Court upheld an injunction ordering Sea Shepherd to keep away from Japanese whaling ships in the Southern Ocean.
