Anti-whaling group Sea Shepherd says it has cut ties with one of its most prominent members for violating its rules against carrying weapons.
New Zealander Pete Bethune is on trial in Japan charged with illegally boarding a Japanese whaler.
In a statement, Sea Shepherd said a bow and arrows had been found on the ship he had been captaining, the Ady Gil.
The group said that while Mr Bethune had not planned to use the weapons, his carrying of them was "unacceptable".
The statement, dated 4 June, praised Mr Bethune for his work during Sea Shepherd's campaign to disrupt Japan's whaling hunt in the Southern Ocean of the Antarctic in late 2009 and early 2010.
But it said the bow and arrows found to have been on board the high-tech Ady Gil speedboat were contrary to Sea Shepherd's "stance of aggressive but non-violent direct action".
The group said it would continue to support Mr Bethune during his trial in Japan, but that he would no longer "be formally associated with, or be a representative of the Sea Shepherd Conservation Society, because his methods are not in complete alignment with the organisation".
But another Ady Gil crew member, Jason Stewart, told New Zealand's TV3 News that Sea Shepherd had always known about the bow and arrows.
In a TV3 interview recorded before the Antarctic campaign, Mr Bethune displayed the weapons and said they would be used to shoot "nasty chemicals" into dead whales so the whaling ships would not take them on board.
Mr Bethune is facing five charges in Japan after he boarded a Japanese whaling ship, the Shonan Maru 2, in the Antarctic in February.
He said he wanted to perform a citizen's arrest of its captain and present a bill for damage to the Ady Gil, which had earlier been destroyed in a crash with the whaler.
But he was instead detained on board and taken to Japan, where he was arrested.
He has pleaded guilty to charges of trespassing, vandalism, possession of a knife and obstructing business, but denied assault. He faces up to 15 years in prison if convicted.
Japan abandoned commercial whaling in 1986 after agreeing to a global moratorium - but international rules allow it to continue hunting under the auspices of a research programme.
It says the annual hunt catches mostly minke whales, which are not an endangered species.
Conservationists say the whaling is a cover for the sale and consumption of whale meat.