An initial investigation is understood to have ruled out an explosion on board the vessel in waters off Shandong
An initial investigation of the submarine disaster which killed 70 Chinese sailors shows the men died of suffocation, and that an explosion appeared to be unlikely, according to a report.
The entire crew and several observers on board the Ming class No 361 submarine were still at their posts when rescuers found the missing vessel, the Wen Wei Po newspaper reported.
The submarine, which was taking part in a training exercise, lost contact with the command centre several hours before the disaster in waters off the coast of Shandong's Yantai City, the newspaper cited a mainland military source as saying.
The submarine was discovered when fishermen saw a periscope poking out of the water and reported their finding to the authorities.
The report suggests the submarine was found either floating near the surface or in water shallow enough that the periscope could reach the surface.
Based on the evidence at the scene, investigators were expected to focus on possible mechanical problems or human error, the report said.