The Natanz nuclear facility in Iran mysteriously lost power on Sunday, Iranian officials said, a blackout that came during negotiations in Vienna aimed at reinvigorating the nuclear deal with Tehran that the Trump administration left.
Power was cut across the facility, Behrouz Kamalvandi, a civilian nuclear program spokesman, told Iranian state television, The Associated Press reported.
“We still do not know the reason for this electricity outage and have to look into it further,” Mr. Kamalvandi said. “Fortunately, there was no casualty or damage, and there is no particular contamination or problem.”
Malek Shariati Niasar, an Iranian lawmaker who serves as a spokesman for the Parliament’s energy committee, wrote on Twitter that the outage was “very suspicious,” A.P. reported. He raised the possibility of “sabotage and infiltration.”
Suspicion in Iran after such disruptions has often focused on Israel, which has sabotaged the nuclear program in the past and regards Iran as its most potent military adversary. But neither the Israeli military nor the Defense Ministry would comment on the matter on Sunday.
Israel welcomed President Donald J. Trump’s repudiation of the nuclear deal three years ago, and it has expressed deep concern about President Biden’s intentions to restore it.
The disruption at Natanz comes at a delicate time — barely a week after diplomatic talks about the accord began in Vienna, and one day after Iran started operating new centrifuges that enrich uranium.
While there is no direct dialogue between Iran and the United States at the talks, the other participants in the agreement — Britain, China, France, Germany and Russia, under the chairmanship of the European Union — are engaging in a form of shuttle diplomacy.
One working group is focusing on how to lift economic sanctions imposed by the Trump administration, while another is looking at how Iran can return to the terms that set limits on enriched uranium and the centrifuges needed to produce it.
Iran has said that its nuclear ambitions are peaceful, and that while it intends to steadily resume nuclear activities prohibited under the deal, it could easily reverse course if the sanctions were rescinded. On Saturday, President Hassan Rouhani of Iran celebrated the inauguration of Iranian centrifuges that shorten the time needed to enrich uranium, the fuel for nuclear bombs.
But Mr. Rouhani also insisted that Iran’s efforts were not intended to produce weapons.
“If the West looks at the morals and beliefs that exist in our country, they will find that they should not be worried and sensitive about our nuclear technology,” Mr. Rouhani said in remarks reported by Iran’s Mehr News Agency.
Word of the Natanz outage came as Lloyd Austin, the U.S. defense secretary, was in Israel on Sunday for talks with Prime Minister Benjamin Netanyahu and the country’s defense minister, Benny Gantz.
At the meeting, Mr. Gantz said, “We will work closely with our American allies, to ensure that any new agreement with Iran will secure the vital interests of the world and the United States, prevent a dangerous arms race in our region and protect the State of Israel.”