The Labour Party is backing calls for the release of a New Zealand anti-whaling activist being held in Japan.
Sea Shepherd activist Peter Bethune was arrested on the charge of trespass on Friday for boarding a whaling patrol boat without invitation in Antarctic waters.
Japan's coastguard, which has handed over Mr Bethune to Tokyo prosecutors, says if found guilty on charges of trespass, Peter Bethune could face up to three years in prison or fines of up to 100,000 yen.
The New Zealand and Australian Green parties on Saturday called on Wellington and Canberra to intervene and ask the Japanese authorities to have Mr Bethune freed.
Now Labour foreign affairs spokesperson Chris Carter says Mr Bethune is a brave protester, not a criminal, and should be brought home immediately.
The Government says it is offering consular assistance to Mr Bethune, but will let Japanese law take its course.
Australian Greens leader Bob Brown says he is backing an international campaign to free Mr Bethune.
Mr Brown says he will not let people forget about Mr Bethune's plight.
New Zealand Foreign Affairs Minister Murray McCully says the Japanese authorities are behaving correctly towards Mr Bethune.
Transport Minister Steven Joyce says he will not be raising whaling during his visit to Tokyo for a one-day ministerial aviation security conference.
Sea Shepherd says the arrest of Mr Bethune in Japan is ridiculous, and the anti-whaling group will stand by him and help with his defence.
The Shonan Maru 2 was involved in a collision with the protest boat Ady Gil in the Southern Ocean two months ago.
Sea Shepherd spokesperson Paul Watson says the Japanese skipper, not Mr Bethune, should have been arrested. He says the Japanese ship destroyed the Ady Gil and almost killed six people, yet has escaped without a reprimand.