TEL AVIV/TEHRAN - An incident at Iran's Natanz nuclear facility on Sunday was caused by an act of "nuclear terrorism", the country's nuclear chief Ali Akbar Salehi said, adding that Tehran reserves the right to take action against the perpetrators, Reuters reports.

Israel's Kan public radio cited intelligence sources, whose nationality it did not disclose, as saying that Israel's Mossad spy agency had carried out a cyber attack at the site.

A nuclear facility in Iran suffered “sabotage” a day after it unveiled new uranium enrichment equipment, the country’s top nuclear official says.

After the Natanz nuclear facility ground to a halt, Israeli intelligence sources were quoted in Hebrew-language media claiming credit for the attack.

They said that a cyber attack by the Mossad foreign intelligence agency inflicted “severe damage at the heart of Iran’s enrichment programme”.

The blackout injected new uncertainty into diplomatic efforts that began last week to salvage the 2015 nuclear deal repudiated by the Trump administration.

Iran did not say precisely what had caused the blackout at the heavily fortified site, which has been a target of previous sabotage, and Israel publicly declined to confirm or deny any responsibility. But American and Israeli intelligence officials said there had been an Israeli role, according to the New York Times.

Two intelligence officials briefed on the damage said it had been caused by a large explosion that completely destroyed the independent — and heavily protected — internal power system that supplies the underground centrifuges that enrich uranium.

The officials, who spoke on the condition of anonymity to describe a classified Israeli operation, said that the explosion had dealt a severe blow to Iran’s ability to enrich uranium and that it could take at least nine months to restore Natanz’s production.

Iran’s leverage in new talks sought by the Biden administration to restore the nuclear agreement could be significantly compromised. Iran has said it will take increasingly strong actions prohibited under the agreement until the sanctions imposed by President Donald J. Trump have been rescinded.