Sweden Boards Sanctioned Tanker Suspected of Sailing Under False Flag

Swedish authorities have boarded a sanctioned oil tanker in the Baltic Sea after determining the vessel may be operating under a false flag, marking the second maritime intervention near the southern Swedish port of Trelleborg in less than a week.

The Swedish Coast Guard, supported by the Swedish Police, boarded the 228-meter tanker Sea Owl I at approximately 20:30 local time on March 12 in Swedish territorial waters. Authorities have opened a preliminary investigation into suspected violations related to lack of seaworthiness.

The tanker was displaying the Comorian flag, but Swedish officials said the vessel does not appear in the Comoros ship register, raising suspicions it may be sailing under a false or unverifiable flag state.

“Our overall assessment is that the risk of safety deficiencies on board is high,” said Daniel Stenling, Deputy Chief of Operations at the Swedish Coast Guard. “On this basis, the vessel cannot be allowed innocent passage. The threats to maritime safety and the environment are too high.”

Under international maritime law, ships operating without a verifiable flag state may lose certain protections normally afforded under the principle of innocent passage, giving coastal states legal grounds to intervene.

The boarding operation was planned in advance and involved both the Coast Guard and Swedish Police. Coast Guard personnel are currently aboard the vessel conducting searches, reviewing documentation, and interviewing crew members as part of the investigation, which is being led by Swedish prosecutors.

Additional Swedish authorities may become involved depending on what investigators uncover.

According to the Coast Guard, Sea Owl I is a 2007-built tanker that has transported oil products between Russia and Brazil in recent years. At the time of the boarding, the vessel was reportedly sailing in ballast from Santos, Brazil to Primorsk, Russia.

The tanker is also listed under European Union sanctions, adding further scrutiny to the case.

The incident follows a similar operation just days earlier involving the general cargo ship Caffa, which Swedish authorities boarded near Trelleborg on March 6 after determining the vessel was likely operating as a stateless ship due to unverifiable flag status.

That vessel was later placed under a prohibition of vessel operation by the Swedish Transport Agency, while its captain became the subject of a criminal investigation including suspected use of false documentation.

Together, the two interventions highlight a growing trend of more assertive maritime enforcement in European waters, as authorities increasingly target vessels suspected of false flagging, sanctions evasion, or opaque ownership structures.

“Sweden protects the law of the sea and the rules-based order that we have jointly agreed on,” Stenling said. “The Coast Guard’s responsibility is to ensure that the regulations at sea are followed. We will intervene against vessels that violate them and that disrupt the safety of our territorial waters.”

For now, authorities say the investigation into Sea Owl I remains ongoing as personnel continue examining the vessel and its documentation at sea.

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