Greenland police said they arrested Paul Watson, a Canadian-American environmental activist and vocal opponent of whaling, on Sunday on an international arrest warrant issued by Japan.
Paul Watson was arrested as his ship docked in Nuuk, the capital of Greenland, police said in a statement.
He will be brought before a district court with a request to be detained pending a decision on his possible extradition to Japan, the statement said.
The Captain Paul Watson Foundation said more than a dozen police officers boarded the vessel and took Watson away in handcuffs when it stopped to refuel.
The foundation said the ship, accompanied by 25 volunteer crew members, was en route to the North Pacific with a mission to intercept another Japanese whaling ship.
The foundation said in an emailed statement that it “believes the arrest is related to an earlier Red Notice issued for Captain Watson’s previous anti-whaling operations in the Antarctic region.”
“We implore the Danish government to release Captain Watson and not accept this politically motivated demand,” Locky MacLean, the foundation’s director, wrote in the statement.
Greenland is an autonomous territory of Denmark.
Mr. Watson, a 73-year-old Canadian-American citizen, is a founder and former director of the Sea Shepherd Conservation Society whose direct-action tactics, including high-seas clashes with whalers, have attracted the support of high-profile celebrities and landed him on the reality TV series Whale Wars.
However, it also brought him into conflict with the authorities. He was arrested in Germany in 2012 on an extradition warrant from Costa Rica, but escaped bail after learning that he was also being extradited by Japan, which accused him of endangering the lives of whalers during operations in the Southern Ocean. He has since lived in countries including France and the United States.
Mr Watson, who left Sea Shepherd in 2022 to start his own organisation, was also a leading member of Greenpeace but left the organisation in 1977 over disagreements over its aggressive tactics.
According to its foundation, Mr. Watson’s current ship, the M/Y John Paul DeJoriawas to sail through the Northwest Passage to the North Pacific to confront a newly built Japanese factory whaling ship, “a murderous enemy devoid of compassion and empathy, bent on the destruction of the most intelligent sentient and self-aware beings of the sea.”