The Swedish Coast Guard said it boarded and took control of a suspected stateless vessel in Swedish waters of the Baltic Sea on Friday, and it was carrying out investigations on the ship.
"At 15:50 today, the coast guard took control of a vessel with unclear flag status and thus suspected of being a stateless vessel," it said in a statement, adding that the boarding had taken place off the coast of the southern Swedish town Trelleborg.
The ship Caffa was sailing under a Guinean flag, but the coast guard said it regarded the vessel to be stateless, "based on national and international legislation". Swedish police said the ship was suspected of sailing under a false flag.
According to ship-tracking service Marine Traffic, Caffa is a 96-metre general cargo ship.
Sweden's minister for civil defence, Carl-Oskar Bohlin, said in a post on social media that the ship was a freighter on Ukraine's sanctions list.
"The ownership structure is unclear and there are suspicions that the vessel is not insured. As recently as this summer, the ship is said to have changed from a Russian to a Guinean flag," Bohlin wrote.
The coast guard said it had launched a preliminary investigation into suspected violation of maritime law regarding lack of seaworthiness.
"The coast guard has personnel on board to gather information about the condition of the vessel and crew, conduct searches, and conduct interviews," it added.
(Reporting by Greta Rosen Fondahn; Editing by Cynthia Osterman)