(JTA) — The United Nations’ nuclear watchdog reported that Iran has built an extension to its military facility at Parchin. A segment of the confidential report seen by the Reuters news agency said that while Iran has largely been complying with agreements on curtailing its nuclear program, its activity at the site since February 2012 has likely undermined the International Atomic Energy Agency’s ability to “conduct effective verification.” “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 [been] constructed,” the IAEA report was quoted by Reuters last week as saying.

Activities at the site since 2012, during a time that Iran stonewalled IAEA requests to visit the site or receive information on it, have undermined the agency’s ability to verify intelligence suggesting that Tehran conducted tests relevant to nuclear bomb detonations at the site in the past, diplomats said August 27. Specifically, the IAEA believes Tehran may have experimented there with high-explosive detonators for nuclear arms.

Iranian Foreign Minister Mohammad Javad Zarif denied the allegations, saying his country was merely repairing roads near the Parchin site and not hiding evidence from the nuclear facility.