"India's entry is done," Alain Bugat, the head of France's Atomic Energy Commission (CEA), told AFP.

"The six partners accepted that India also become a partner," he said.

The International Thermonuclear Experimental Reactor (ITER) to be built in Cadarache, in southern France, over a decade starting 2007, now counts seven partners: the European Union, Japan, the United States, Russia, South Korea, China and India.

The EU 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, but added that a formal announcement had not yet been made.

"The negotiations are at an advanced stage with India but there is not yet a political signature," he said.

"But there are no longer any obstacles to overcome," he said.

ITER aims to create fusion energy -- the same sort of process that occurs at the heart of the Sun, one that is much more powerful than in conventional nuclear power plants -- and find ways to harnass it to supplant the world's reliance on dwindling fossil fuels.

ITER will be home to 400 scientists, two-thirds of them foreign. The reactor is expected to have a life-span of 40 years.