Russia's Nerpa nuclear attack submarine, damaged in a fatal accident during tests in November last year, has entered service with the Russian Navy after successfully passing final trials, a Pacific Fleet spokesman said Monday.

The submarine was officially commissioned in the town of Bolshoy Kamen in the Primorye Territory in the Russian Far East, home to the Amur shipyard Vostok repair facility which carried out the submarine's repairs.

On November 8, 2008, while the Nerpa was undergoing sea trials, its onboard fire suppression system activated, releasing a deadly gas into the sleeping quarters. Three crewmembers and 17 shipyard workers were killed. There were 208 people, 81 of them submariners, onboard the vessel at the time.

Following repairs, which cost an estimated 1.9 billion rubles ($65 million), the submarine had been cleared for final sea trials.

The final sea trials had showed that the Nerpa nuclear submarine was ready to enter service with the Russian Navy.

The submarine will be subsequently leased to the Indian Navy under the name INS Chakra. India reportedly paid $650 million for a 10-year lease of the 12,000-ton K-152 Nerpa, an Akula II class nuclear-powered attack submarine.

Akula II class vessels are considered the quietest and deadliest of all Russian nuclear-powered attack submarines.

VLADIVOSTOK, December 28 (RIA Novosti)