Swedish police Friday treating very seriously reports of a mysterious presumed pirate attack on a Maltese- registered freighter in the Baltic Sea, according to dpa. Swedish deputy crime police chief Tommy Hydfors confirmed to the German Press Agency dpa the report that eight heavily-armed masked men on Friday last week boarded Finnish-owned freighter Arctic Sea from a rubber dinghy. According to the ship's 15-member Russian crew, the armed men claimed to be drug enforcement agents and thoroughly searched the ship, reacting violently to anyone who got in their way, including using a rifle butt to knock out teeth from one crew member.