The United States, the European Union, China, India, Russia, Japan and South Korea signed an accord in 2006 to build a $12.8 billion experimental fusion reactor at Cadarache, southern France, aimed at revolutionizing global energy use for future generations.

The International Thermonuclear Experimental Reactor, or ITER, members have said no single country can afford the immense investment needed to move the science forward.

Salehi, Iran’s nuclear chief, said Iran was willing to join any international grouping to offer its expertise to promote the project. However, he said Iran will go its own way should the world not welcome it.