Tokyo, Japan (CNN) -- Japanese prosecutors indicted Friday an activist from New Zealand on five criminal counts, including tresspassing, in an incident earlier this year in the waters off the Antartic where Japan conducts its annual whaling expedition.
If convicted, activist Peter James Bethune, 44, faces years in prison and thousands of dollars in fines.
He is accused of jumping aboard the Shonan Maru 2, the security ship of a Japanese whaling fleet, after the Ady Gil, of which Bethune was captain, sank.
Bethune belongs to the activist group Sea Shepherd Conservation Society. The group said the New Zealander was attempting to make a citizen's arrest of the Shonan Maru 2 skipper for the January collision that sank the Ady Gil, a futuristic vessel used to intercept and block harpoon ships.
Bethune was taken into custody in February aboard the Shonan Maru 2 and was formally arrested when the ship returned to Japan last month.
Video: 'Whale Wars' ship hits whaler
The Tokyo District Public Prosecutors Office indicted Bethune on five criminal counts: illegal entrance to a vessel or trespassing; damage to property; assault (for throwing butyric acid onto the Shonan Maru 2); forcible obstruction of business (interrupting the whaling expedition); and violation of arms control law (Bethune was in possession of a long survival knife, which is illegal in Japan).
The Bethune case highlights an ongoing feud between Japanese whaling fleets and conservation agencies, especially the hardline Sea Shepherd.
Activists have used their own boats to interfere with whaling ships, thrown butyric acid -- found in rancid butter and vomit -- and fired paint guns. The Japanese, in turn, have repelled protesters with water cannons.
