Danish sailors seized weapons from a ship off Somalia's coast, captured six suspected pirates and then destroyed the vessel, Denmark's navy said on Wednesday.
Navy spokesman Kenneth Nielsen said the suspects were released after questioning.
"They had not committed anything criminal at sea — they were just on the wrong boat, with the wrong gear at the wrong time," Nielsen said. "They had equipment on board that could be used in piracy."
He said the vessel was a mother ship to which the pirates attach smaller speedboats they use in attacks on ships off eastern Somalia.
Personnel from the Danish warship Esbern Snare used explosives to destroy the vessel on Tuesday. The Danish ship is part of NATO's counter-piracy force.
Piracy is rife off the coast of Somalia in east Africa, disrupting shipping lanes between Europe and Asia, putting crews and vessels in danger and jacking up insurance rates for shipowners.
"There is a very strong mandate from the U.N. so that international navies can confiscate and destroy equipment related to piracy," Nielsen added.
The captured supply boat was larger than the skiffs commonly used by pirates in raids so it could operate far from the coast, he said.
"Scuppering this vessel ... prevents them from conducting piracy in the middle of the Indian Ocean where it is difficult to find suspected pirates," Nielsen said.