Iran has rejected allegations that it attempted to clear away radioactive traces of suspected nuclear weapons research activities at the Parchin military base outside Tehran.
Foreign Ministry spokesman Ramin Mehmanparast said "nuclear traces cannot be cleaned up or covered."
The United Nations nuclear watchdog, the International Atomic Energy Agency (IAEA), said last week that satellite images suggested there may have been unspecified "ongoing" activities at the Parchin base, and Western diplomats said they suspected Iran was removing evidence from the site.
The Iranian Foreign Ministry spokesman also repeated pledges to provide IAEA inspectors with one-time access to the closed military site. Iran has twice this year refused requests by a visiting IAEA team to inspect Parchin.
Tehran says its nuclear program is for peaceful civilian purposes only.
With AFP, AP, and Fars reporting