The confidential IAEA report, obtained by Reuters, said:

“Since (our) previous report (in May), at a particular location at the Parchin site, the agency has continued to observe, through satellite imagery, the presence of vehicles, equipment, and probable construction materials. In addition, a small extension to an existing building appears to have constructed.”

Diplomats say any activities Iran has undertaken at Parchin since 2012 are likely to have undermined the agency’s ability to verify intelligence suggesting Tehran previously conducted tests there relevant to nuclear bomb detonations.

Under a “roadmap” accord Iran reached with the IAEA parallel to its groundbreaking deal with the global powers, the Islamic Republic is required to give the Vienna-based watchdog enough information about its past nuclear activity to allow to write a report on the long vexed issue by year-end.