A court in Greenland has again extended the time in custody for a prominent anti-whaling activist as Denmark considers an extradition request from Japan.

The court ruled that Canadian-American Paul Watson must remain in detention until October 2 while Denmark’s justice ministry considers the request.

Greenland is an autonomous territory of Denmark, which does not have an extradition treaty with Japan.

Watson is the former head of the Sea Shepherd Conservation Society, whose high-seas confrontations with whaling vessels have drawn widespread attention.

He was arrested on July 21 when his ship docked in Greenland’s capital.

Japan’s coast guard sought his arrest over an encounter with a Japanese whaling research ship in 2010, when he was accused of obstructing the crew’s official duties by ordering the captain of his ship to throw explosives.

Watson is said to face up to 15 years in prison.

In a statement, the prosecution noted that Watson has appealed against the decision by the Nuuk district court to the High Court of Greenland. One of Watson’s lawyers, Julie Stage, confirmed the appeal.

She said: “We are not satisfied with the outcome.”

Omar Todd, the chief executive and co-founder of the Captain Paul Watson Foundation, has visited Watson in the detention centre outside Nuuk.

Mr Todd said Watson “is doing fine. He is, I guess, getting a little bit accustomed to the life there at the moment. But he is doing well. He is determined and optimistic”.

Watson, who left Sea Shepherd in 2022, was also a leading member of Greenpeace but left in 1977 amid disagreements over his aggressive tactics.