NEW DELHI, April 4: India returned to the elite club of countries with a nuclear-powered submarine on Wednesday when it inducted a new vessel leased from Russia.

India is particularly keen to strengthen its maritime capabilities, given China's pursuit of a powerful "blue water" navy which Delhi sees as a threat to key shipping routes in the Indian Ocean and Indian energy assets in the South China Sea.

"This will be a big boost for the Indian navy," Antony told reporters after commissioning the vessel.

"The INS Chakra will ensure security and sovereignty of the country," he said in televised remarks.

The 8,140-tonne submarine, capable of firing a range of torpedoes as well as nuclear-tipped Granat cruise missiles, was offered to India by Moscow on a 10-year lease - a deal greeted with alarm and anger by Pakistan.

India is currently completing the development of its own Arihant-class nuclear-powered submarine and INS Chakra II is expected to help crews train for the domestic boat's introduction into service this year.

"Our crews will get the experience of operating under water for several months at a go, unlike with the conventional diesel electric submarines, which have to come to surface at regular intervals," an unnamed navy official told the PTI news agency.The Akula II-class craft is the first nuclear-powered submarine to be operated by India since it decommissioned its last Soviet-built vessel in 1991.

With INS Chakra and the INS Arihant expected to start operational patrols by the end of the year, India will soon have two nuclear submarines guarding its vast maritime boundaries.

India signed up for the Russian submarine, formally known as Nerpa, in 2004 and it was slated to be handed over in 2009 but testing problems delayed the delivery.

The submarine was undergoing trials in the Sea of Japan in 2008 when its fire-fighting system accidentally went off, filling it with a toxic gas that killed 20 people on board.

Media reports also said India had complained that the weapons navigation system did not work to New Delhi's specifications.

Russia supplies 70 per cent of India's military hardware but New Delhi has been unhappy about delays to arms orders from Moscow and has looked to other suppliers including Israel and the United States in recent years.

Five other countries deploy nuclear-powered submarines - Britain, China, France, the United States and Russia.

India has promised not to arm the submarine with nuclear-tipped cruise missiles under its obligations to international treaties it adopted after conducting a series of atomic tests in the 1990s.-AFP