DUBAI, United Arab Emirates (AP) -- Iran blamed Israel on Monday for a sabotage attack on its underground Natanz nuclear facility that damaged centrifuges it uses to enrich uranium, warning that it would avenge the assault.
Israel has not claimed responsibility for the attack. However, suspicion fell immediately on it as Israeli media widely reported that the country had orchestrated a devastating cyberattack that caused the blackout.
Sunday's assault and Foreign Ministry spokesman Saeed Khatibzadeh's comments blaming Israel could imperil ongoing talks in Vienna with world powers about saving a tattered accord aimed at curbing Iran's nuclear program.
If Israel was responsible, it would further heighten tensions between the two nations, already engaged in a shadow conflict across the wider Middle East. Israeli Prime Minister Benjamin Netanyahu, who met Sunday with U.S. Defense Secretary Lloyd Austin, has vowed to do everything in his power to stop the reviving of the nuclear deal.
At a news conference at Israel's Nevatim air base Monday, where he viewed Israeli air and missile defense systems and its F-35 combat aircraft, Austin declined to say whether the Natanz attack could impede the Biden administration's efforts to re-engage with Iran in its nuclear program.
"Those efforts will continue," Austin said. The previous American administration under Donald Trump had pulled out of the nuclear deal with world powers, leading Iran to begin abandoning its limits.
Details remained scarce about what happened early Sunday at the facility. The event was initially described as a blackout caused by the electrical grid feeding its above-ground workshops and underground enrichment halls.
"The answer for Natanz is to take revenge against Israel," Khatibzadeh said. "Israel will receive its answer through its own path." He did not elaborate.
Khatibzadeh acknowledged that IR-1 centrifuges, the first-generation workhorse of Iran's uranium enrichment, had been damaged in the attack, but did not elaborate. State television has yet to show images from the facility.
A former chief of Iran's paramilitary Revolutionary Guard said the attack had also set off a fire at the site and called for improvements in security. In a tweet, Gen. Mohsen Rezaei said that the second attack at Natanz in a year signaled "the seriousness of the infiltration phenomenon." Rezaei did not say where he got his information.
Iranian Foreign Minister Mohammad Javad Zarif separately warned Natanz would be reconstructed with more advanced machines. That would allow Iran to more quickly enrich uranium, complicating talks on the deal.
"The Zionists wanted to take revenge against the Iranian people for their success on the path of lifting sanctions," Iran's state-run IRNA news agency quoted Zairf as saying. "But we do not allow (it), and we will take revenge for this action against the Zionists."
Officials launched an effort Monday to provide emergency power to Natanz, said Ali Akbar Salehi, the head of Iran's civilian nuclear program. He said the sabotage had not stopped enrichment there, without elaborating.
The IAEA, the United Nations body that monitors Tehran's atomic program, earlier said it was aware of media reports about the blackout at Natanz and had spoken with Iranian officials about it. The agency did not elaborate.
Natanz has been targeted by sabotage in the past. The Stuxnet computer virus, discovered in 2010 and widely believed to be a joint U.S.-Israeli creation, once disrupted and destroyed Iranian centrifuges there during an earlier period of Western fears about Tehran's program.
In July, Natanz suffered a mysterious explosion at its advanced centrifuge assembly plant that authorities later described as sabotage. Iran now is rebuilding that facility deep inside a nearby mountain. Iran also blamed Israel for the November killing of a scientist who began the country's military nuclear program decades earlier.
Multiple Israeli media outlets reported Sunday that an Israeli cyberattack caused the blackout. Public broadcaster Kan said the Mossad was behind the attack. Channel 12 TV cited "experts" as estimating the attack shut down entire sections of the facility.
While the reports offered no sourcing for their information, Israeli media maintains a close relationship with the country's military and intelligence agencies.
"It's hard for me to believe it's a coincidence," Yoel Guzansky, a senior fellow at Tel Aviv's Institute for National Security Studies, said of the blackout. "If it's not a coincidence, and that's a big if, someone is trying to send a message that 'we can limit Iran's advance and we have red lines.'"
It also sends a message that Iran's most sensitive nuclear site is penetrable, he added.
Netanyahu late Sunday toasted his security chiefs, with the head of the Mossad, Yossi Cohen, at his side on the eve of his country's Independence Day.
"It is very difficult to explain what we have accomplished," Netanyahu said of Israel's history, saying the country had been transformed from a position of weakness into a "world power."
Israel typically doesn't discuss operations carried out by its Mossad intelligence agency or specialized military units. In recent weeks, Netanyahu repeatedly has described Iran as the major threat to his country as he struggles to hold onto power after multiple elections and while facing corruption charges.