India's navy was supposed to lease the brand-new Russian nuclear submarine that suffered an accident over the weekend which killed 20 people, news reports said Monday.

An Indian naval spokesman would not comment Monday on leasing this or any submarine from Russia — but his boss has said previously that India was interested.

The Akula-class sub was undergoing trials in the Sea of Japan when its fire-extinguishing system activated in error, spewing Freon gas that suffocated the victims and injured 21 others.

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Russia's navy said the submarine itself was not damaged in Saturday's accident and returned to its Pacific coast port Sunday under its own power.

Russia's top business dailies Kommersant and Vedomosti reported Monday that the Nerpa was to be handed over to India's navy next year under a 10-year, $650-million lease.

India previously leased a nuclear-powered submarine from the Soviet Union in 1988-1991, and India's navy chief, Adm. Sureesh Mehta, was quoted as saying that India was negotiating with Moscow to lease two Russian nuclear submarines, the first of which could arrive next year.

Armed with cruise missiles capable of hitting targets 1,860 miles away, Akula-class subs are considered the quietest and deadliest of Russian attack submarines. A sub of that class could unsettle the military balance of power in Asia, dramatically bolstering India's navy capability as it jockeys with China for influence over energy supply routes in the Indian Ocean.

Phone calls to China's defense and foreign ministries seeking comment rang unanswered Monday night.

Vedomosti quoted an unidentified shipping industries official as saying the sub was intended for India's navy, which has already named it the Chakra.

Indian naval spokesman Cmdr. Nirad Sinha would not confirm whether the Nerpa was to be leased and said no Indians were on board the submarine when the accident occurred.

"It's a Russian submarine, and any concerns are Russian concerns," Sinha told The Associated Press.

Indian news reports said Monday the submarine was to join the southern Asian country's navy in August. The Indian Express newspaper also reported that Indian sailors had been scheduled to head to Russia later this month for on-board training.

Kommersant, meanwhile, quoted an unnamed shipyard official as saying the delivery of the submarine to India, originally set for August 2007, had been postponed twice already.

As investigators tried to determine what activated the firefighting system, Russian naval experts said overcrowding and human errors may have contributed to the accident.

The Nerpa had 208 people aboard when the accident occurred, including 81 seamen, according to the navy. Akula-class subs normally carry a crew of 73.

Retired submarine Capt. Alexander Pokrovsky said in a commentary that sea trials often pose increased safety risks.

Pokrovsky also criticized Freon-based fire-extinguishing systems, saying they are dangerous for the crew and need to be replaced with safer equipment.

Individual breathing kits should have saved the crew, but some former submariners said civilian shipyard workers usually have little experience in using them. Seventeen of those killed in the accident were civilians, the Russian navy said.

"Civilians were supposed to undergo training, but it usually is pretty informal," said Igor Kurdin, who heads an association of former submariners. He speculated the fire system could have been triggered by something as simple as someone smoking a cigarette near a safety gauge.

Some commentators also speculated there might not have been enough individual breathing kits for all those aboard during the test.