Russian President Dmitry Medvedev signed agreements on Friday to develop new nuclear plants in India.
The Indian government said in a statement the deal will allow Russia to build more reactors at the Kudankulam nuclear power plant in the southern Indian state of Tamil Nadu and plants elsewhere in the country.
Earlier this year India signed a nuclear pact with the United States, giving New Delhi access to civilian nuclear fuel and technology on the international market for the first time in three decades.
It overturned a US ban on nuclear trade instituted after India first tested an atomic device in 1974.
India and Russia also signed a contract for India to buy 80 Mi-17 transport helicopters (Mi-17), worth more than $US1 billion.
The two also signed a deal to cooperate on future manned space flights and on building an astronaut training centre.
India plans to send an astronaut into space with its own rocket by 2014.