Iran has escalated its uranium enrichment further with the use of advanced machines at its underground Fordow plant in a setup that can more easily change between enrichment levels, the U.N. atomic watchdog said in a report on Saturday seen by Reuters.
Western diplomats have long expressed concern about devices this cascade, or cluster, of centrifuges is equipped with.
The use of these so-called modified sub-headers means Iran could switch more quickly and easily to enriching to higher purity levels.
While Iran is required to inform the International Atomic Energy Agency about such a switch, if it chose not to, it might escape detection for some time as there is currently a lag between Iran's enrichment and IAEA inspectors' verification of what is produced.