A fire broke out at Iran's Natanz nuclear facility but there were no casualties and the site is operating as usual, Iranian officials said on Thursday.
The Natanz Fuel Enrichment Plant (FEP), covering 100,000 square meters and built eight meters underground, is one of several Iranian facilities monitored by the United Nations nuclear watchdog.
Iran's Atomic Energy Organisation initially reported that "an incident" had ocurred at the facility.
"There were no casualties or damages and the nuclear site is operating as usual," the organisation's spokesman, Behrouz Kamalvandi, was quoted as saying by semi-official Tasnim news agency.
The governor of Natanz city, Ramazanali Ferdowsi, later said the incident was caused by fire, adding that firefighters had been sent to the site. He gave no further details about the cause of the blaze, Tasnim reported.
A team of experts from the Atomic Energy Organisation is investigating the cause of the incident.
"There is no concern about the possibility of contamination as one of the sheds which was inactive and under construction was damaged and not the facility itself," Kamalvandi told state news agency IRNA.
Iran agreed to curb its nuclear program in exchange for the removal of most international sanctions in a deal reached between Tehran and six world powers in 2015.
But Tehran has gradually reduced its commitments to the accord since U.S. President Donald Trump's administration withdrew from the agreement in 2018 and reimposed and intensified sanctions that have battered Iran's economy.
The deal only lets Iran accumulate enriched uranium with just over 5,000 of its first-generation IR-1 centrifuges at Natanz. It lets Iran use small numbers of more advanced models for research, without producing enriched uranium.