The sailors were killed on July 1 when a fire broke out as their deep-water research submarine was surveying the seafloor near the Arctic, the Russian Defense Ministry has said. President Vladimir Putin disclosed for the first time on Thursday that the secret military submarine was nuclear-powered, prompting the defense minister to assure him its reactor had been safely contained.

The 14 Russian sailors killed in last week’s nuclear submarine fire may have prevented a “planetary catastrophe,” a high-ranking officer has reportedly said at their funeral ceremony this weekend.

“With their lives, [the 14 sailors] saved their comrades, saved the ship and averted a catastrophe of planetary scale,” Russia’s independent Open Media news outlet quoted an unnamed high-ranking military official at the funeral as saying on Saturday.

No further details have been provided and The Moscow Times was unable to verify the authenticity of the reported comments.

The main cause of the incident was a fire in the vessel’s battery compartment, Defense Minister Sergei Shoigu told Putin on Thursday.

"The nuclear reactor on the vessel is completely isolated," Shoigu told Putin. "All the necessary measures were taken by the crew to protect the reactor, which is in complete working order."

Moscow's slow release of information about the incident has been compared to the opaque way the Soviet Union handled the 1986 Chernobyl nuclear disaster. It also drew parallels with the 2000 sinking of the nuclear-powered Kursk submarine, which claimed 118 lives.

Russia says the details of the submarine involved in the latest accident are classified. A tribute to the men said they had served on board a nuclear-powered deep-sea submersible known by the designation AS-31.

Made out of a series of interconnected spheres which allow it to resist water pressure at great depths, Western military experts have suggested it is capable of probing and possibly even severing undersea communications cables.

Russian media have previously reported, without official confirmation, that the vessel is designed to carry out special operations at depths where regular submarines cannot operate.

Putin bestowed four of the dead submariners with Russia's highest state award and granted another top state award to the 10 others on Friday.

Reuters contributed reporting to this article.