Sea Shepherd is claiming victory after Japan temporarily suspended its annual whale hunt in the Southern Ocean.
On Wednesday, the anti-whaling group claimed two of its boats, the Steve Irwin and the Bob Barker, were rammed by a Japanese ship in Australian Antarctic waters.
It said the attacks happened after they were ordered to leave the area by one of the boats in the Japanese whaling fleet, the ABC reports.
Japan's fisheries agency confirmed that one of its factory ships, the Nisshin Maru, rammed two boats belonging to Sea Shepherd.
Japan's Institute of Cetacean Research has announced it has stopped work for the time being because it is too difficult to refuel.
Sea Shepherd says it will keep following the Japanese vessels in the Southern Ocean, despite the temporary halt.
Captain Paul Watson said on Thursday his group will stay with the whalers until the season ends in 18 days.
The Australian maritime safety authority is investigating the latest clash between Japanese whalers and Sea Shepherd.