The fire aboard a submersible, which killed 14 submariners, started in the battery compartment, Defense Minister Sergei Shoigu reported to Russian President Vladimir Putin on Wednesday.
"The main cause of the incident has been established: it was a fire in the battery compartment and then it spread," the Kremlin website quoted Shoigu as saying.
An operational headquarters comprising the submersible’s designers and industry representatives is carrying out its work to investigate the incident, the defense chief said, TASS reports.
Fire on the submersible
Russia’s Defense Ministry said in a statement released on Tuesday that 14 submariners had died in a fire on a submersible in Russian waters on July 1.
"On July 1, fourteen submariners - sailors died in Russian territorial waters as a result of inhaling combustion products aboard a research submersible designated for studying the seafloor and the bottom of the World Ocean in the interests of the Russian Navy after a fire broke out during bathymetric measurements," the ministry said in a statement.
The fire was extinguished "thanks to the self-sacrificing actions of the crew," the statement said.
The submersible is currently staying at Severomorsk, the main naval base of Russia’s Northern Fleet. The causes of the incident are being investigated.
On Putin’s instruction, Shoigu arrived in Severomorsk on Wednesday where he held a meeting on establishing the causes of the deadly fire aboard the submersible. Shoigu noted that the crew had acted "heroically" and primarily rescued a civilian aboard the submersible after which they continued struggling for the vessel’s survivability.
All the dead sailors will be recommended for state awards posthumously while all the necessary assistance and support will be rendered to their families, the defense minister said.
Russia’s defense chief also held a separate meeting with representatives of the enterprise that had developed the research submersible and had given instructions to work out and implement measures within the shortest time possible to repair the submersible and bring it into service again.