(CNN)A deepwater submersible that caught fire Monday was nuclear-powered, according to Russia's President Vladimir Putin.
Putin's comments came during a conversation with the country's defense chief, who confirmed that the incident was caused by a fire in a battery compartment. The Kremlin had initially been reluctant to release information about the blaze, which left 14 sailors dead due to smoke inhalation, calling it a state secret.
The submersible, which is smaller than a submarine and has limited power reserves, was carrying out research in Russian territorial waters at the time of the fire and is now at the naval base in Severomorsk on the Barents Sea.
According to a Kremlin transcript released Thursday, Putin asked Defense Minister Sergei Shoigu about the status of the vessel's "nuclear power unit."
"Mr. President, the nuclear power unit has been sealed off," Shoigu, who had visited Severomorsk, replied.
"The crew has taken the necessary measures to save the unit, which is in working order," Shoigu added.
He confirmed to Putin that the vessel could be repaired and said "the main reason for the tragedy: a fire in the battery (compartment) that spread out."
"We are using the services of the submarine designers and industry representatives to assess the volume and time frame of repairs," he added.
Shoigu is overseeing the probe into the incident. On Wednesday, he indicated there were some survivors and that 10 of the victims were captains. "Fourteen crew members were killed, the rest were saved," he said according to RIA-Novosti.
"Seven of the dead were captains of the first rank, and three were captains of the second rank. Two were Heroes of Russia. All deceased officers will be presented with state awards posthumously," he added.
He said the submariners evacuated a "civilian representative of the industry" from "the compartment engulfed in fire." They then proceeded to lock "the hatchway to stop the fire from spreading all over the apparatus and were fighting till the end so the vessel survived."
In the Kremlin transcript released Thursday, he told the President that assistance measures were being given to the sailors' families.
"Assistance measures include good education for those children who are still studying and a decent standard of living for everyone, just as we did following similar bitter tragedies," he said.
The blaze is one of the deadliest incidents the Russian navy has experienced in years.
Twenty people were killed on board a Russian nuclear submarine in 2008, when a fire extinguishing system was triggered accidentally. In 2000, more than 100 men died on the Kursk, a nuclear-powered submarine, when two explosions in its bow caused it to sink to the floor of the Barents Sea.