The approved completion cost of the Kudankulam Nuclear Power project was Rs 13,171 crore, officials said.
"The completion cost is now expected to be Rs 15,824 crore and the project is expected to be completed in 2012-13," they added.
The delay has been attributed to various reasons including delivery schedule of certain components from Russia and the ongoing protests in Kudankulam against the nuclear power plant.
The total expenditure on the project till September this year has been Rs 14,122 crore.
As per the original plan, the first unit was to be commissioned in December 2007, which was revised to mid-2010. This was further revised to September 2011 when the anti-nuclear protests broke out in Kudankulam.
The first Inter-Governmental Agreement for setting up two 1000 MW light water reactors was signed between India and the erstwhile USSR in 1988.
A supplement to the agreement was signed with the Russian Federation in 1998. The ground breaking for the Kudankulam project took place in September 2001 and the first pour of concrete took place in March 2002.
NPCIL and Russia's Atomstroy Export formally inked a deal for building two more civil nuclear reactors of 1,000 MW each at Kudankulam last year.
A total of 12 Russian nuclear power reactors are expected to come up in India of which six would be built between 2012 and 2017.