Swedish police have raided a Russian-linked cargo ship off the northwestern coast of Gotland, with the National Task Force taking part in the overnight operation.

Axar.az reports, citing TV4 Nyheterna, that officers boarded the vessel, which is more than 80 metres long, during the night leading into Saturday to inspect its crew and travel documents.

The ship belongs to a shipping company previously investigated over suspected links to Russian hybrid attacks and intelligence operations. According to TV4, the crew members aboard the vessel are Russian citizens, although police declined to confirm their nationalities.

The company has offices in Russia's Kaliningrad exclave, where it says it recruits its crews.

The suspicions include the possibility that the ships were used as platforms for drones operated by Russian intelligence services. European intelligence sources have assessed that the vessels are highly likely to be acting in the interests of the Russian state.

Police declined to comment on which units took part in the raid, saying only that they had deployed the resources necessary for the operation.