BERLIN — Greenland police said they arrested a veteran environmental activist and anti-whaling campaigner on Sunday on an international arrest warrant issued by Japan.

Paul Watson was arrested when his ship docked in Nuuk, Greenland’s capital, a police statement said. He will be brought before a district court with a request to detain him pending a decision on his possible extradition to Japan, the statement said.

The Captain Paul Watson Foundation said that more than a dozen police boarded the vessel and led Watson away in handcuffs when it stopped to refuel. The foundation said the ship, along with 25 volunteer crew members, was en route to the North Pacific on a mission to intercept a new Japanese whaling ship.

“The arrest is believed to be related to a former Red Notice issued for Captain Watson’s previous anti-whaling interventions in the Antarctic region,” the foundation said in an emailed statement.

“We implore the Danish government to release Captain Watson and not entertain this politically-motivated request,” Locky MacLean, a foundation director, said in the statement.

Greenland is an autonomous territory of Denmark.

Watson, a 73-year-old Canadian-American citizen, is a former head of the Sea Shepherd Conservation Society whose direct action tactics, including high-seas confrontations with whaling vessels, has drawn support from A-list celebrities and featured in the reality television series “Whale Wars.”

However, it has also brought him into confrontation with authorities. He was detained in Germany in 2012 on a Costa Rican extradition warrant, but skipped bail after learning that he was also sought for extradition by Japan, which has accused him of endangering whalers’ lives during operations in the Antarctic Ocean. He has since lived in countries including France and the United States.

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

According to his foundation, Watson’s current ship, the M/Y John Paul DeJoria, was due 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 hell bent on destroying the most intelligent self-aware sentient beings in the sea.”