Russia will deliver a nuclear submarine to India by the end of the year, Russia’s navy chief was quoted as saying on Friday by state news agency RIA.

India sees Russia as a strategic counterweight to China but New Delhi has been upset by repeated delays to major weapons orders from Moscow, including the Admiral Gorshkov heavy aircraft carrier.

The date for delivering the Nerpa submarine to India, Russia’s close economic and political partner since Soviet days, has repeatedly been put back.

"We shall definitely supply this vessel to the customer by the end of this year," RIA quoted navy commander Admiral Vladimir Vysotsky as saying.

Vysotsky said an fully trained Indian navy crew were ready to receive the submarine, which some Russian media reported last year had already been handed over to India.

The Nerpa, an attack submarine codenamed "Akula" — or "Shark" — by NATO, is usually armed with torpedoes and cruise missiles. It can go down to depths of 600 meters (2000 ft) for about 100 days. It can carry 73 people.

Construction of the Nerpa began in 1991 — the year the Soviet Union collapsed — but funding was frozen in the chaotic 1990s and the submarine was only launched and started sea trials in 2008, according to Russian media.

Twenty people died on the Nerpa after inhaling the toxic gas used as a fire suppressant when its fire extinguishing system switched on unexpectedly at sea trials in November 2008.

The accident was the deadliest to hit Russia’s navy since August 2000, when the Kursk nuclear submarine sank beneath the Barents Sea, killing all 118 sailors on board.

India agreed to buy the Gorshkov aircraft carrier and have it upgraded in 2004. But Moscow has repeatedly asked for more money and the latest price tag reported for the ship is $2.3 billion. It has still not been delivered to India.