(Reuters) - Iran has refrained from expanding tests of more efficient models of a machine used to refine uranium under a nuclear agreement with six world powers, a U.N. report shows, allaying concerns it might be violating the accord.
Tehran's development of advanced centrifuges is sensitive because, if successful, it could enable it to produce potential nuclear bomb material at a rate several times that of the decades-old version of the machine now in use.
An interim accord in 2013 between Iran and the United States, France, Germany, Britain, China and Russia stipulated Tehran could continue its "current enrichment R&D (research and development) practices", implying they should not be stepped up.