The UN's nuclear watchdog says Iran is preparing for a possible major expansion of uranium enrichment in an underground complex.
The Fordow site is buried deep inside a mountain
The number of enrichment centrifuges there has more than doubled to 2,140 from 1,064 in May
However, the new machines are not yet operating
The International Atomic Energy Agency also says "extensive activities" at Iran's Parchin military complex will hamper its investigation of possible past nuclear weapons development work there - if inspectors are granted access.