A Russian maritime journal has reported that a Maltese-flagged Finnish cargo ship with a Russian crew has been missing for 12 days in the Atlantic Ocean, Press TV reported.
The vessel's last known location was off the coast of Portugal, the Russian maritime journal Sovfrakht reported on its website on Sunday.
The Finnish bulk carrier, Arctic Sea, failed to arrive at the Algerian port of Bejaia on August 4 as planned.
"The vessel has literally disappeared since July 28: there is no communication, and neither the ship-owners nor the relatives [of crewmembers] nor Lloyd's have any information about its whereabouts," RIA Novosti news agency said, quoting the Sovfrakht report.
Unknown gunmen posing as policemen attacked the same vessel on July 24 off the Swedish coast, tying up the 15-member crew for 12 hours and searching the ship, according to earlier media reports.
Bloomberg reported on its website that the gunmen, who are believed to be pirates, assaulted the crew members during the search of the ship's timber cargo.
Swedish officials investigating the rare attack said it was the most unusual they had ever witnessed.
Some Russian media said a multi-national police force is hunting the waters to locate the ship.