Explosives were used to cut the electricity power lines to Iran's Fordow underground enrichment plant last month in an apparent attempt to sabotage Tehran's atomic advances, its nuclear energy chief said on Monday.
It was believed to be the first time Iran has mentioned the incident, which Iranian atomic energy organization chief Fereydoun Abbasi-Davani said took place on Aug. 17.
He also told the annual member state gathering of the International Atomic Energy Agency (IAEA) that "the same act" had been carried out on power lines to Iran's main enrichment plant near the central town of Natanz, without giving a date.
Abbasi-Davani made clear his view that sabotage would not be successful in slowing Iran's nuclear program, which the West suspects is aimed at developing an atomic bomb capability but which Tehran says is purely peaceful.
Iran has often accused Israel and Tehran's Western enemies of being behind the assassination of Iranian nuclear scientists and of trying to damage its nuclear program in other ways, such as cyber attacks.
Abbasi-Davani said explosives had been used to cut power lines from the city of Qom to the Fordow underground uranium enrichment plant on Aug. 17. The next morning, he said, IAEA inspectors had asked for an unannounced visit to Fordow.
"Does this visit have any connection to that detonation? Who, other than the IAEA inspector, can have access to the complex in such a short time to record and report failures?" Abbasi-Davani told the gathering in Vienna.
"It should be recalled that power cut-off is one of the ways to break down centrifuge machines," he said, referring to the machines used to enrich uranium, which can have both civilian and military purposes.
He did not say whether the power had since been restored or give any other details.
Iran uses the Fordow facility to enrich uranium to a fissile concentration of 20 percent, the part of its work that most worries the West as it takes it significantly closer to the 90 percent level needed for bombs. It built the site some 80 metres below rock and soil to better protect it against enemy strikes.
Abbasi-Davani, in unusually strong language in an international forum, also accused the IAEA of a cynical approach and mismanagement and suggested that "terrorists and saboteurs" might have infiltrated it.
Abbasi-Davani told the IAEA gathering that included senior US and other Western officials: "Plotters of attack against Iran's nuclear facilities have realized, through the IAEA published reports, that they have not gained any success in this regard."
Iranian experts have devised "certain ways through which nuclear facilities remain intact under missile attacks and air raids," he said.