* Indian PM Singh has formal talks with Medvedev
* Cold War allies agree on military, nuclear energy ties
* Breakthrough reached on aircraft carrier deal - source (Writes through with military, nuclear cooperation plans)
By Denis Dyomkin
MOSCOW, Dec 7 (Reuters) - Russia and India stressed their strategic partnership on Monday, agreeing to boost military ties and cooperate in the civilian use of nuclear technology, but gave few details.
"We have discussed the key aspects of our economic and military-technical cooperation," Russian President Dmitry Medvedev told Indian Prime Minister Manmohan Singh at the start of their official talks in the Kremlin. The two had met for an informal dinner late on Sunday.
"We look into the future with optimism," Medvedev said. "We will witness the signing of a whole range of important documents reflecting our strategic partnership in its entire diversity."
Russia sees India, a Cold War ally, as an important partner whose influence will expand in Asia.
The two delegations later signed agreements on "military-technical cooperation", a term routinely used by the Kremlin to refer to arms sales, for the period 2011-12 and agreed that Russia would build more nuclear reactors in India.
Russia and India, which agreed the outlines of a 10-year weapons deal in October that could be worth at least $10 billion, are building a modern supersonic fighter aircraft invisible to radar like the U.S. F-22 Raptor stealth fighter.
Officials said before the talks that Singh might sign weapons orders including a $1 billion deal for 80 Russian Mi-17 helicopters and contracts for fitting Brahmos missiles to Russian-made Sukhoi fighter planes.
No concrete details of any arms sales were available.
NUCLEAR ENERGY
Medvedev and Singh both expressed support for greater cooperation in the civilian use of nuclear energy.
The nuclear deal could significantly increase atomic fuel exports from Russia to India and would lead to the construction of more Russian reactors in India, both sides said.
"Today we have signed an agreement which broadens the reach of our cooperation beyond the supply of nuclear reactors to areas of research and development and a whole range of areas of nuclear energy," Singh said at a Kremlin news conference.
Sergei Kiriyenko, the head of the Russian state nuclear agency Rosatom, said Russia next year would commission the first reactor at an Indian nuclear power plant in Kudankulam.
"All in all, there will be six reactors at Kudankulam, maybe eight ... It's still under discussion," he told reporters.
Singh said India had identified an additional site for a nuclear power plant in the state of West Bengal.
He said Rosatom estimated its potential contract volumes in India at "several dozens of billion of dollars", with "12 or maybe even more (nuclear) blocks to be built". "The scale of cooperation is really huge," he said.
Settling an issue that had troubled relations between Moscow and New Delhi, Russia said on Monday it would finally deliver a refurbished aircraft carrier to India.
Along with China, India is one of Russia's biggest clients for arms sales but New Delhi has been upset in recent years by long delays in the delivery of the refurbished Soviet-era carrier Admiral Gorshkov under a $1.6 billion contract.
"Discussions between India and Russia on the delivery of the Admiral Gorshkov have been finalised, and the deal will be accomplished," a Kremlin source told reporters on condition of anonymity. He gave no time frame for the deal and Indian officials were not immediately available for comment.
In July, Medvedev took the rare step of publicly scolding the Russian shipbuilder for the delays. (Writing by Dmitry Solovyov; Editing by Andrew Dobbie)