VIENNA -- The International Atomic Energy Agency (IAEA) will hold an emergency meeting of its Board of Governors on June 23, after the United States attacked Iran's nuclear facilities overnight, the agency said on Sunday.

"Following attacks on three nuclear sites in Iran -- including Fordow -- the IAEA can confirm that no increase in off-site radiation levels has been reported as of this time," the United Nations agency said on social platform X on Sunday morning.

The agency said it would provide further assessments of the situation in Iran as more information becomes available.

US President Donald Trump said earlier on Saturday that the United States has completed attacks on three nuclear sites in Iran, including Fordow, Natanz and Esfahan.

Iranian Foreign Minister Seyed Abbas Araghchi said Sunday that the US strikes on Iranian nuclear facilities were "outrageous" and "will have everlasting consequences," and Iran "reserves all options" to retaliate.

Before the US attack, IAEA Director General Rafael Grossi said on Saturday that a large nuclear complex in Esfahan has been targeted for a second time during Israel's attacks on Iran over the past nine days, with several more buildings struck.

The facilities targeted either contained no nuclear material or small quantities of natural or low-enriched uranium, meaning any radioactive contamination is limited to the buildings that were damaged or destroyed, Grossi said.

"This nuclear complex in Esfahan -- one of the key sites of the Iranian nuclear program -- has repeatedly been attacked and extensively damaged. Based on our analysis of the nuclear material present, we don't see any risk of off-site contamination. Nevertheless, as I have repeatedly stated, nuclear facilities should never be attacked," Grossi said.