A New Zealand anti-whaling activist has been handed over to Japan for possible trial.

Japanese prosecutors are believed to be holding Peter Bethune, who was handed over to them by the Japanese coastguard after being detained by whalers in the area.

44-year-old Bethune could face up to three years in jail if he is charged and convicted over the secret boarding of a Japanese whaling ship in the Antarctic in February.

Bethune is the captain of the expensive powerboat the Ady Gil, which was destroyed in a confrontation with the Shonan Maru 2 in January.

He later boarded the Japanese whaling ship to try to confront the captain but was apprehended.