An explosion was heard at the Natanz nuclear facility heard Saturday night, the Iranian Student News Agency reported.
According to Sputnik, the blast has not yet been confirmed by officials.
Fars reported that an unmanned aerial vehicle (UAV) was shot down above the Natanz facility. According to that report, the Iranian air defense systems were activated in order to defend against a target southeast of the nuclear facility.
According to an Iranian report, the explosion occurred 20 kilometers away from the facility.
Maariv quoted Iranian media as saying that the Iranian Air Force conducted an test in order to examine its response time for attacks on Natanz.
The explosion occurred as talks on the renewal of a nuclear deal between Iran and global powers continue.
Reuters quoted a student news agency as saying that the explosion had been heard in the sky above the town of Natanz, but noted that official confirmation has not yet been issued.
"Local sources have reported hearing a large explosion in the Natanz sky. No official source has yet confirmed or denied the report," websites, including Faraunews, quoted the Daneshju (Student) News Agency as reporting.
An April explosion at the Natanz facility reportedly destroyed as much as 90% of the facility's centrifuges. Intelligence officials told The New York Times that the resulting damage would take nine months to repair.