Some data about the deadly fire onboard a Russian submersible in the Barents Sea is classified and won’t be made public, Kremlin Spokesman Dmitry Peskov told reporters on Wednesday answering a question on the vessel’s type, TASS reports.

"The Supreme Commander-in-Chief has all the information, but this data cannot be made public, because this refers to the category of absolutely classified data," Peskov stressed. "

"There is classified information, this top secret is kept in the interests of a state and national security," Peskov said, insisting that "this is absolutely normal practice, when information is not revealed, there is nothing illegal here."

Peskov declined to comment whether the submersible had a nuclear reactor, saying that this is a matter of the Russian Defense Ministry.

Fourteen submariners died in a fire that broke out aboard a deep-sea underwater research vessel in Russian waters on July 1, the Defense Ministry said in a statement released on Tuesday. The accident occurred while the submersible was conducting bathymetric measurements, namely examining the sea bottom, currents and the depths. The fire was extinguished "thanks to the self-sacrificing actions of the team," the statement read. Two of the sailors were Heroes of Russia and seven others were captains of the first rank. Now the vessel is at the Arctic port of Severomorsk, the main base of Russia's Northern Fleet. The causes of the accident are being investigated.

Russian President Vladimir Putin held a meeting with Defense Minister Sergei Shoigu. Putin instructed the minister to fly to Severomorsk to ensure a thorough investigation.

Read more: Fire kills 14 Russian sailors aboard navy research submersible