A rogue wave has damaged an anti-whaling boat in the Southern Ocean, breaking a hole in its hull.
The Brigitte Bardot was chasing the Japanese whaling fleet and is currently about 1,500 miles southwest of Fremantle, Australia.
The Sea Shepherd flagship, the Steve Irwin, is on its way to help the damaged boat.
It could take about 20 hours to get there, said Sea Shepherd founder Captain Paul Watson.
“Right now the safety of my crew on the Brigitte Bardot is our priority and we intend to reach the crew and then do what we can to save our ship,” he said.
It would be returned to Australia while another boat continued to chase the whaling fleet, he added.
The ship was chasing the Japanese factory ship Nisshin Maru in six-metre (20-foot) waves when a swell slammed into its port side.
One of its pontoons has been badly damaged. The crack was reported to be getting wider but Mr Watson said he was confident the vessel would stay afloat until the rescue boat arrived.
The 10-strong multi-national crew on board includes three Britons, three Americans, an Australian, a Canadian, a Belgian and its South African captain Jonathan Miles Renecle.
Japan’s fleet sails south to the Antarctic in the autumn each year, returning the following spring.
There has been a ban on commercial whaling for 25 years, but Japan catches about 1,000 whales each year in what it says is a scientific research programme.
Critics say it is commercial whaling in another guise.
Last year the Japanese fleet returned early, citing safety concerns, after confrontations with Sea Shepherd – an activist group that follows the fleet and disrupts its hunt.
In the past there have been collisions between its vessels and the whaling fleet, and its activists have also boarded Japanese vessels.
Last year, a Sea Shepherd speedboat, the ‘Ady Gil’, sunk after a collision with a Japanese ship.
Japan’s Fisheries Minister Michihiko Kano said earlier this year that extra ships would escort the fleet to the Antarctic.