The Sea Shepherd Conservation Society says Captain Paul Watson was arrested in Frankfurt over the weekend and will be extradited to Costa Rica on an outstanding arrest warrant.
The Sea Shepherd says in a statement that the arrest warrant stems from a 2002 incident involving a Costa Rican vessel illegally hunting for shark fins in Guatemalan waters.
On Twitter late Sunday, Watson tweeted: "I am currently being held in Frankfurt on charges from Costa Rica. Court appearance in the morning."
The group says while the Sea Shepherd boat was escorting the Costa Rican vessel back to port, a Guatemalan gunboat was dispatched to intercept the group’s crew.
According to a statement on the group’s website, the crew of the Costa Rican vessel accused the Sea Shepherds of trying to kill them, "while the video evidence proves this to be a fallacy."
The Sea Shepherd says their ship later encountered a Costa Rican gun boat, the crew of which has accused Watson of attempted murder.
The Sea Shepherd Conservation Society was formed in 1977 and has had a controversial history.
The group sends vessels to confront the Japanese fleet each year, trying to block them from firing harpoons at whales.
The group’s tactics have drawn praise from supporters and vehement attacks from critics.
According to Sea Shepherd, Watson is being assisted in jail by European Parliament vice-president Daniel Cohn Bendit and European deputy Jose Bove.
"Our hope is that these two honourable gentlemen can set Captain Watson free before this nonsense goes any further," Sea Shepherd said.
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