The Bulgaria riverboat was flooded with 125 tons of water a minute last month because of an incompetent crew, a negligent ship owner and the captain's mistakes, the Federal Transportation Inspection Service said Monday.
The Bulgaria sank in less than three minutes on the Volga River, killing 122 of the 201 people on board. The transportation watchdog reported the findings of a probe into the incident on its web site.
"The captain and owner of the ship failed to comply with safety regulations … and the poor qualification and discipline of the crew led to the accident," the agency said.
Numerous mistakes and violations resulted in the Bulgaria being flooded and capsizing during a storm, it said.
The agency also confirmed earlier reports about four small holes in the ship's hull that contributed to the sinking. The finding was reported by media last week but then was dismissed by the Investigative Committee, which is conducting its own inquiry into the disaster.
The committee did not comment on Monday's report. It has said the Bulgaria sank because it was overloaded and suffered mechanical problems, including engine and radio malfunctions.
A leading maritime expert, Mikhail Voitenko, editor of the Maritime Bulletin, told Novaya Gazeta on Thursday that the Investigative Committee's explanation was a "fake" because neither overloading nor engine or radio problems could have caused the ship to go under.
"Have they watched too much 'Titanic' or what?" Voitenko said. The committee has not commented on his allegations.
Two suspects have been arrested, the director of the travel agency that operated the boat, Svetlana Inyakina, and the boat inspector who authorized the 46-year-old Bulgaria to sail despite its problems, Yakob Ivashov.
The ship's captain, Alexander Ostrovsky, drowned in the accident. New legislation allows investigators to charge dead suspects, but it remained unclear whether Ostrovsky faces posthumous prosecution.