India also said that it had a deal to build at least 12 other reactor units with Russian collaboration, and that the cabinet had approved a civil nuclear deal with Australia for fuel supply.
A senior government source had told Reuters earlier this month that the contract with Westinghouse, a unit of Toshiba Corp <6502.T>, to build the reactors in Prime Minister Narendra Modi's home state of Gujarat could be finalised in the first half of next year.
India plans to build roughly 60 reactors, which would make it the world's second-biggest nuclear energy market after China.
It wants to increase its nuclear capacity to 63,000 megawatts (MW) by 2032, from 5,780 MW, as part of a broader push to move away from fossil fuels, cut greenhouse gas emissions and avoid the dangerous effects of climate change.
The United States signed a pact with India in 2008, opening the way for nuclear commerce.
But hopes that reactor makers would get billions of dollars of new business diminished after India adopted a law in 2010 giving the state-run operator Nuclear Power Corp of India Ltd (NPCIL) the right to seek damages from suppliers in the event of an accident.
Officials in India have been trying to assuage suppliers' concerns, including by setting up an insurance pool with a liability cap of Rs. 1,500 crore ($226.16 million).
A final hurdle - ratification of the International Atomic Energy Agency's Convention on Supplementary Compensation for Nuclear Damage (CSC) - is expected within weeks, the government official told news agency, Reuters. The CSC requires signatories to shift liability to the operator and offers access to relief funds.'
In a statement earlier this month, Westinghouse said it expected India would move towards a framework that satisfies the CSC and channels accident liability exclusively to the operator. The statement made no reference to ongoing negotiations.
Negotiators from Westinghouse and Indian operator NPCIL have held several rounds of talks on the nuclear plant in Mithi Virdi, the government official said.
NPCIL declined to comment on the negotiations. Federal minister for Atomic Energy Jitendra Singh told parliament earlier this month that talks were going on with French and US firms to arrive at project proposals. He offered no details.
But the government source said that Westinghouse and NPCIL were negotiating all six reactors in one go, instead of an earlier plan to strike deals for two at a time.
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.