Saboteurs have tried to damage Iran's uranium enrichment plants by bombing power lines to the sites, head of Iran's Atomic Energy Organization Fereydoun Abbasi said Monday in Vienna, dpa reported.
The International Atomic Energy Agency (IAEA) might be involved in the incidents, Abbasi noted.
His comments at the IAEA's annual general conference came amid efforts by the nuclear agency to start investigating alleged nuclear weapons projects in Iran. Also Monday, the European Union announced plans to resume nuclear talks with Iran.
"Terrorists and saboteurs might have intruded in the agency and might be making decisions covertly," Abbasi said.
On August 17, electric power lines supplying the fortified Fordow enrichment site near Qom were cut with the use of explosives, he said, adding that power outages lead to damages of uranium centrifuges.
"Then, in the early hours of next morning, an agency inspectors requested an unannounced inspection. Does this visit have connection to that detonation?" he asked, speaking through a translator.
The power lines to the Natanz enrichment plant have also been hit by a blast, he added.
The United States, Israel and many other countries fear that Iran might use enriched uranium for nuclear weapons, while Tehran maintains it needs the material to fuel reactors.
In 2010 some 30,000 Iranian computers were infected with the sophisticated Stuxnet worm, which appeared to target computers connected to uranium-enriching centrifuges at nuclear sites.
Computer experts have speculated that the worm was developed by either Israel or the US to derail Iran's disputed nuclear programmes.