"We have taken the necessary measures and are taking stock of the damage" caused by the strikes, said the head of the Atomic Energy Organization of Iran, Mohammad Eslami, in a statement aired on state television.

"Plans for restarting (the facilities) have been prepared in advance, and our strategy is to ensure that production and services are not disrupted," he added.

The United States struck the Fordo, Isfahan and Natanz uranium enrichment facilities on Sunday.

US President Donald Trump called the strikes a "spectacular military success". The extent of the damage is unknown.

An adviser to Iran's supreme leader, Ayatollah Ali Khamenei, said his country still had stocks of enriched uranium and that "the game is not over".

Israel announced on Monday that it had again bombed the Fordo site, buried under a mountain south of Tehran, to "obstruct access routes".