Sweden is investigating a tanker that is suspected of being part of the sanctioned Russian “shadow fleet,” according to the Scandinavian country's civil defense minister.

The Swedish Coast Guard said it boarded and detained the Jin Hui on Sunday on suspicion of flying a false flag while transiting Swedish waters.

The vessel was sailing through the Baltic Sea under a Syrian flag, the coast guard said in a statement. There are also concerns related to the vessel’s seaworthiness.

The Jin Hui — which remained anchored off Trelleborg on Monday — is currently on European Union, U.K.…