A court martial in Russia’s Far Eastern port city of Vladivostok acquitted the two men last October on the basis of the jury verdict which was overturned by the Supreme Court this past May.

Their lawyer said he could appeal the ruling.

The Pacific Fleet court ruled that the case would be reviewed by a jury.

More than 200 people were onboard the Nerpa attack submarine during sea trials in the Sea of Japan in November 2008 when a fire-suppressant gas mixture was released. Another 21 people were injured in Russia’s worst naval accident since the sinking of the Kursk nuclear submarine in 2000.

The Nerpa’s captain, Dmitry Lavrentyev, and engineer Dmitry Grobov, who allegedly activated the sub’s fire safety system “without authorization and for no reason,” have been charged with negligence.

The Nerpa was undergoing shakedown trials and had 208 people aboard, nearly three times its normal complement.

A former senior medical officer with the Pacific Fleet alleged in May that the Nerpa's firefighting system contained a "lethal" mixture of freon and trichloroethylene - a commonly used industrial solvent which is highly toxic and corrosive - rather than pure freon.

Workers at the Amur Shipyard, where the submarine was built, said in an open letter in the same month that Lavrentyev and Grobov were "scapegoats" and that the disaster was the result of "corruption and disintegration of the military-industrial sector."