A New Zealand activist who boarded a Japanese whaling ship in the Antarctic is being taken to Japan for questioning.
Peter Bethune, a member of the Sea Shepherd anti-whaling group, had wanted to make a citizen's arrest of the ship's captain for "attempted murder".
He has been detained on the Shonan Maru 2 since boarding it on Monday.
Japan has six whaling vessels in the Antarctic, where whalers and activists regularly clash during the hunt season.
Chief Cabinet Secretary Hirofumi Hirano told a news conference the country was preparing to bring him to Japan to be questioned under Japanese law.
''We would like to decide whether to file criminal charges against him under Japanese law," Japan's Kyodo news agency quoted Mr Hirano as saying.
Mr Bethune is suspected of illegally boarding the Shonan Maru 2 in the early hours of Monday morning by cutting through its protective netting.
He had said he wanted to arrest the ship's captain, Hiroyuki Komiya, for attempted murder, following a crash between the Shonan Maru 2 and Sea Shepherd's Ady Gil speedboat in January.
Sea Shepherd says the Shonan Maru 2 deliberately crashed into the Ady Gil, destroying the hi-tech vessel.
The whalers said the activists tried to tangle a rope in their propeller.
Mr Bethune also wanted to present Mr Komiya with a bill for the damage.
Sea Shepherd warned that any trial would be "a rallying point for an international campaign" against whaling.
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.
The BBC's Tokyo correspondent says few Japanese eat whale regularly, but many object to international pressure to stop whaling, which they see as part of the country's tradition.