WASHINGTON — Iran’s most senior atomic energy official revealed on Monday that separate explosions, which he attributed to sabotage, had targeted power supplies to the country’s two main uranium enrichment facilities, including the deep underground site that American and Israeli officials say is the most invulnerable to bombing.

The official, Fereydoon Abbasi, a nuclear scientist who narrowly escaped an assassination in his car nearly two years ago, just before he was appointed to lead the Atomic Energy Organization of Iran, said one of the attacks occurred on Aug. 17, a day before international inspectors arrived at the underground site.

The most recent report by the International Atomic Energy Agency, the United Nations arm that conducts the inspections, said nothing about power cutoffs. On Monday, a spokesman for the agency would not comment on whether power to the site had been disrupted.

There was no way to verify Mr. Abbasi’s assertions; he also contended that the I.A.E.A. had been infiltrated by “terrorists and saboteurs,” suggesting they were responsible for the attacks. But if they were acts of sabotage, as he claimed, they would raise the question of whether Israel, the United States or some groups within Iran had moved beyond cyberattacks to take other steps, short of a military attack, to disable Iran’s nuclear fuel plants.