“The IAEA has been informed by Iran about an incident in a building at the site of the Natanz uranium enrichment facility early on Thursday. Iran also informed the IAEA late on Thursday that the fire was quickly extinguished and that there had been no nuclear material or other radioactive material in the building. Iran said the cause was not yet known, adding there were no injuries or radioactive contamination,” the UN nuclear watchdog said in a statement on Friday.

It added, “The Natanz site is under IAEA safeguards, including both safeguards verification and JCPOA verification and monitoring. The Agency can confirm that there were no IAEA safeguards inspectors present at the time, and that the location where the incident occurred does not contain nuclear materials.

“The Agency has been in contact with relevant Iranian authorities to confirm there will be no impact on its safeguards verification activities, which are expected to continue as before. IAEA inspectors are present on a regular basis at Natanz.”

Iran’s Supreme National Security Council (SNSC) said the “main cause” of the incident had been determined and will be announced at an appropriate time.

SNSC Spokesman Keyvan Khosravi said on Friday that experts from different sectors started investigating “different hypotheses” about the incident at the Natanz site in central Iran immediately after its occurrence, and have determined its main cause.

“Due to some security considerations, the cause and manner of this incident will be announced at a proper time,” he added.