India will join six other countries in the 4.6 billion euro ($5.4 billion or Rs 25,000 crore) experimental fusion reactor project.
The International Thermonuclear Experimental Reactor to be built in Cadarache, in southern France, over a decade starting 2007, will have seven partners: the European Union, Japan, the United States, Russia, South Korea, China and India.
The European Union is to put up half the cost of building the reactor, with the rest evenly divided among the other parties.
Francois d'Aubert, France's official representative for the ITER, acknowledged that a technical agreement had been struck welcoming India. He said an agreement was yet to signed but said, "There are no longer any obstacles to overcome," he said.
ITER is the experimental step between today's studies of plasma physics and tomorrow's electricity-producing fusion power plants.
It is based around a hydrogen plasma torus operating at over 100 million °C, and will produce 500 MW of fusion power. The international project works under the auspices of the International Atomic Energy Agency.
It is technically ready to start construction and the first plasma operation is expected in 2016. ITER is to be constructed in Europe, at Cadarache, near Aix-en-Provence, France.