Moscow, Nov 19 (RIA Novosti) The accident on the Russian nuclear submarine Nov 8 that killed 20 people could have been caused by a computer glitch, a Russian daily reported Wednesday. The accident occurred when nuclear submarine Nerpa was undergoing sea trials in the Sea of Japan. Three submariners and 17 shipyard workers died in the accident. There were 208 people, 81 of them submariners, on board the vessel at the time.

“We submariners are unanimous: a computer programme failed. Previously, the submarine fire suppression system had always started manually on the commander’s orders. Now it is launched electronically,” Ensign Yevgeny Ovsyannikov, a technical specialist on the Nerpa, told Komsomolskaya Pravda.

He added that it was the first time this computerized system had been used on the submarine during the sea trials and that the computer had malfunctioned during tests in the dock.

An expert who requested anonymity suggested that a toxic form of Freon could have been used in the fire suppression system.

“A toxic additive, trichlorotrifluoroethane, was used. It is cheaper than pure Freon. Possibly, they simply wanted to economize,” he said.

He added that there were unmistakable signs of poisoning, which could not have been caused by Freon: “People were collapsing as though they had been shot.”

Breathing Freon is generally safe, but if the concentration in the air is high it can cause suffocation.

It was previously reported that the deaths were caused by a crew member activating the fire safety system without permission or by the wrong data being entered into the temperature sensor.

The submarine’s nuclear reactor was not affected by the accident, which took place in the nose section, and radiation levels on board remained normal.

The incident is the worst for the Russian Navy since the sinking of the Kursk nuclear submarine in 2000 when all of its 118 sailors died.

The construction of the Akula II class Nerpa nuclear attack submarine started in 1991, but was suspended for over a decade due to a lack of funding. Akula II class vessels are considered the quietest and deadliest of all Russian nuclear-powered attack submarines.

Based in the Russian Far Eastern city of Komsomolsk-on-Amur, the Amur shipyard has built 270 vessels, including the Nerpa and another 55 nuclear submarines since it was established in 1936.