Undated file picture shows the Natanz uranium enrichment facility in Natanz, 300 km south of Tehran, capital of Iran.(Photo: Xinhua)

An electrical power problem caused an incident at Iran's Natanz underground nuclear facility on Sunday, Iranian Press TV reported, a day after Tehran launched new advanced uranium enrichment centrifuges at the site.

"The incident caused no casualties or contamination," Iran's Atomic Energy Organization spokesman Behrouz Kamalvandi said, adding that "electricity was affected at the Natanz facility," which is located in the desert in the central province of Isfahan.

The underground Natanz site is the centerpiece of Iran's uranium enrichment program and monitored by inspectors of the International Atomic Energy Agency, the UN nuclear watchdog.

"The cause of this incident is under investigation," Kamalvandi told Iran's semi-official Fars news agency.

A spokesman for the UN nuclear watchdog said by email, "We are aware of the media reports. We have no comment at this stage." 

In July 2020, a fire broke out at the Natanz facility, which the government said was an attempt to sabotage Iran's nuclear program. 

In 2010, the Stuxnet computer virus, widely believed to have been developed by the United States and Israel, was discovered after it was used to attack Natanz.

Tehran and Washington have been trying to revive Iran's 2015 nuclear deal with major powers after former US president Donald Trump abandoned it three years ago. 

Trump reimposed sanctions that had been lifted on the Islamic Republic, and brought in many more.