Japanese media are reporting that an arrest warrant has been issued for Paul Watson, leader of the environmental group Sea Shepherd.
The Kyodo news agency says the Japanese coastguard has obtained a warrant for Mr Watson's arrest on the grounds that he and members of his group tried to obstruct operations by Japan's whaling fleet.
Another member of the Sea Shepherd group, New Zealander Pete Bethune, is in a Japanese jail on five charges, including trespass, resulting from a collision in February that resulted in the sinking of Sea Shepherd trimaran Ady Gil.
But Mr Watson has dismissed the move, saying he has no intention of going to Japan, and authorities there should focus on the Japanese captain whose ship rammed the Ady Gil.
