A spokesman for Iran's civilian nuclear program said Sunday an “accident” has struck the electrical distribution grid of the country's Natanz nuclear facility, without elaborating.
Behrouz Kamalvandi made the comment Sunday, saying there were no injuries or pollution caused by the incident.
"The incident caused no casualties or pollution," Kamalvandi said, adding that "electricity was affected at the Natanz facility."
Malek Shariati Niasar, a lawmaker who serves as spokesman for the Iranian parliament’s energy committee, wrote on Twitter that the incident was “very suspicious,” raising concerns about possible “sabotage and infiltration.” He said lawmakers were pursuing details of the incident as well.
The cause was being investigated, Kamalvandi told Iran's semi-official Fars news agency.
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A spokesman for the UN nuclear watchdog International Atomic Energy Agency said by email: "We are aware of the media reports. We have no comment at this stage."
Another mysterious explosion in July damaged Natanz's advanced centrifuge facility. Iran later called the incident sabotage.
On Saturday, Iranian President Hassan Rohani said that Iran had begun feeding uranium hexafluoride (UF6) gas feedstock into about 30 uranium-enriching centrifuges installed at Natanz.
Furthermore, Rohani said that Iran has started the second stage of producing heavy water – a component of making nuclear weapons and nuclear energy that is not radioactive – at Arak Nuclear Plant. This is yet another breach by Iran of the nuclear accord it signed with world powers in 2015.
Speaking on Iran's annual national nuclear day, Rohani said that, the production capacity of the new advanced IR-5 centrifuges at Natanz is ten times that of the old centrifuges.
Iran's IR-9 centrifuge, when operational, would have the ability to separate uranium isotopes more quickly than the current centrifuges being used, thereby enriching uranium at a faster pace.
A live video link carried on state TV showed Rohani ordering the injection of uranium gas into 164 IR-6 centrifuges, 30 IR-5 centrifuges, and mechanical tests on IR-9 machines with the capacity of 50 early IR-1 machines - a likely new breach of the nuclear deal.
On Friday, the UN atomic watchdog flagged a new breach by Iran of the nuclear deal on the day its representatives met with European mediators in Vienna to revive the agreement, a report by the agency seen by Reuters showed, likely raising tensions with Western powers.
Since January, Iran has begun enriching uranium at up to 20 percent purity, a technical step away from weapons-grade levels, though Iran's leadership insists the country has no desire to develop a nuclear weapon.
Reuters contributed to this report.