Israel appeared to confirm claims that it was behind a cyber-attack on Iran’s main nuclear facility on Sunday, which Tehran’s nuclear energy chief described as an act of terrorism that warranted a response against its perpetrators.

The apparent attack took place hours after officials at the Natanz reactor restarted spinning advanced centrifuges that could speed up the production of enriched uranium, in what had been billed as a pivotal moment in the country’s nuclear program.

As Iranian authorities scrambled to deal with a large-scale blackout at Natanz, which the country’s Atomic Energy Agency acknowledged had damaged the electricity grid at the site, the Israeli defense chief, Aviv Kochavi, said the country’s “operations in the Middle East are not hidden from the eyes of the enemy”.