Media sources reported that a senior Iranian security official claimed that the July 5 explosion at the nuclear facility in Natanz was "security-related" unlike of other recent incidents.
Gholamreza Jalali said the Natanz blast was being investigated by government security forces, but that findings would not be publicized "due to security considerations."
A number of experts have stated that the blast would set Iran's nuclear program as far back as two years.
Jalali said other recent fires in the country were a result of natural circumstances and blamed the media for spreading false rumors.