The anti-whaling group Sea Shepherd has rejected the Japanese government's claims that four people were injured when they threw stink bombs at a whaling vessel earlier today.

Sea Shepherd activists on the Ship the Steve Irwin threw a substance that smells like rancid butter at the Nisshin Maru.

They also threw another substance aimed at making the ship's whale processing deck too slippery to use.

The Steve Irwin's captain Paul Watson says both substances are harmless.

"The material that we throw on board is non-toxic and organic, in fact it's even food grade, so it certainly hasn't injured anybody," he said.

"And I personally saw the impact of every container, and not one container landed anywhere within the proximity to a person."

Foreign minister condemnation

Australia's foreign minister Stephen Smith has condemned the actions of the anti-whaling protestors.

Mr Smith says the Australian embassy in Tokyo has been advised that three or four crew members on board the Japanese ship are being treated by a doctor.

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