Japan’s coast guard on Thursday added a set of new allegations against an anti—whaling activist from New Zealand who is in custody for illegally boarding a Japanese harpoon boat on a whaling expedition

Prosecutors are set to indict Peter Bethune of the U.S.—based Sea Shepherd activist group on Friday.

Mr. Bethune jumped aboard the vessel from a Jet Ski in Antarctic seas in February during Japan’s annual whale hunt.

The 44—year—old was arrested on March 12 for the alleged trespassing immediately after the ship returned to Japan, and has since been in custody in Tokyo.

Coast Guard spokesman Masahiro Ichijo said the agency added new allegations on Thursday: assault, illegal possession of a knife, destruction of property and obstruction of business.

Assault and business obstruction each carries a prison term of up to 15 years or a fine up to 500,000 yen ($5,340). His initial trespassing allegation can bring a prison term of up to three years or a fine up to 100,000 yen ($1,100).

Mr. Bethune has admitted to the allegations, Ichijo said. Mr. Bethune’s Japanese lawyers refused comment.

Japan’s annual whale hunt is allowed by the International Whaling Commission as a scientific programme, but opponents call it a cover for commercial whaling, which has been banned since 1986.

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