Canada was the first nation to make a bid to host the experiment, offering a site at Clarington near Toronto last year. The French government has now offered a site at Cadarache, where the French atomic energy commission (CEA) already has a laboratory. Japan has offered a site at Rokkasho-mura in the Aomori Prefecture, while Spain has proposed a site at Vandellos near Barcelona.

The host will be expected to pay at least half of the cost of ITER and a decision on the site is expected before the end of the year. The negotiators will meet again in Toronto in September, in Aomori in October and in Barcelona in December.