The Iranian Atomic Energy Organization (IAEO) shared a picture of the damaged building, which appeared to show a fire-charred roof, broken doors, and busted windows.
The facility is located in the Iranian province of Isfahan, south of the capital Tehran.
Ramazanali Ferdowsi, the governor of Natanz, said the fire only damaged one building under construction within the complex and did not affect the main area of the nuclear facility, Tasnim reported.
The incident is still under investigation, according to Iran’s state media Press TV, which quoted an unnamed Iranian security official as saying there was “no evidence” of sabotage.
The incident has not interrupted ongoing activities at the site, IAEO spokesman Behrouz Kamalvandi said, according to IRNA.
“IAEO expert teams have been deployed to investigate the factors that lead to damage to the precast steel frame,” said Kamalvandi.
He told Press TV that the incident has not caused any “stoppage” of enrichment work at the facility, which “is done primarily underground,” he said.
It also rejected the possibility that the incident could have caused possible radioactive contamination, Press TV reported. “Contrary to the false propaganda of the enemy and counter-revolutionary media, there has been no contamination because there has been no nuclear material in this shed,” he told Press TV.