Two protesters have been taken into custody after they boarded a Japanese whaling vessel in the Antarctic.
The Japanese claim acid was thrown by the activists (Image: ICR)
The Sea Shepherd campaign group said the two - a Briton and an Australian - had been assaulted and tied to the radar mast by the Japanese crew.
They said they wanted charges of kidnap to be filed in Australia.
Minoru Morimoto, of the Institute of Cetacean Research (ICR), admitted the pair had been detained but denied they had been assaulted or harmed.
He said the Sea Shepherd's accusations that the two men were tied up were "completely untrue".
"It is illegal to board another country's vessels on the high seas. As a result, at this stage, they are being held in custody while decisions are made on their future," he added.
The two - Australian Benjamin Potts and Briton Giles Lane - boarded the Yushin Maru 2 from the Sea Shepherd vessel the Steve Irwin.
In a statement, the group accused the Japanese crew of holding the two men hostage.
"Captain Paul Watson has notified the Australian Federal Police that he would like to see kidnapping charges brought against the Japanese whalers," the statement said.
The campaign group said the pair had intended to deliver a message informing the Japanese that it was now illegal to kill whales, because an Australian court had outlawed the practice.
A Federal Court judgement in Sydney ruled that it was illegal for the Japanese fleet to hunt whales, and ordered them to stop their expedition.
But Tokyo has said in the past that it will ignore any injunction resulting from the case.
The Japanese fleet plans to kill about 900 minke whales and 50 fin whales by mid-April as part of what it describes as a scientific research programme.
But Australia and other nations say the research goals could be achieved using non-lethal methods and call the programme a front for commercial whaling.