Factory trials of the multi-role nuclear submarine, christened INS Chakra which India-will get on a 10-year-lease, commenced on June 11 at the Komsomolsk-on-Amur shipyard and will be followed by sea trials, Russian defence sources said, adding it will be delivered by September 2009.

According to experts, Chakra would help India fill the void caused by the delays in the indigenous Advanced Technology Vessel project to build a nuclear powered, guided missile attack submarine.

Three Indian naval crews for the nuclear submarine have already been trained at the specially set up training centre in Sosnovy Bor near St. Petersburg.

This facility would also be used for training crews for the Indian nuclear submarines of ATV project currently in the advanced stages of development, sources said.

Though they said that India has financed the completion of construction of submarine of project 971 "Shchuka B"(NATO codename Akula) under the USD 650 million deal signed in 2004 as part of the larger Gorshkov package, they did not reveal the cost of the lease of Chakra.

Akula (Shark) is the quietest Russian attack submarine and Chakra has been christened after its predecessor leased by the Indian Navy in 1988 from the erstwhile USSR.