Iran described a blackout on Sunday at its underground Natanz atomic facility as an act of "nuclear terrorism" and now sources say the Mossad is reportedly behind the attack.

According to The Jerusalem Post, Israeli media said the incident, which was originally described as an "accident" by Iran was committed by the Mossad.

Sources told the Post that the event does not appear to be an accident and the damage is greater than Iran had originally reported to the public.

Power was cut across the facility, which is comprised of above-ground workshops and underground enrichment halls, civilian nuclear program spokesman Behrouz Kamalvandi earlier told Iranian state TV.

IDF Chief of Staff Lt.-Gen. Aviv Kohavi remarked on Sunday about Israeli involvement.

"The IDF's actions throughout the Middle East are not hidden from our enemies' vision, who are observing us, seeing our capabilities, and carefully considering their next steps," Kohavi said.

"By virtue of clever operational activities, the past year was one of the most secure years that the citizens of the State of Israel have known," he added. "We will continue to act, combining power and discretion, determination and responsibility - all of this to guarantee the security of the State of Israel."

Sunday's developments also complicate efforts by the U.S., Israel's main security partner, to re-enter the atomic accord aimed at limiting Tehran's program so it can't pursue a nuclear weapon.

As news of the blackout emerged, U.S. Defense Secretary Lloyd Austin landed Sunday in Israel for talks with Prime Minister Benjamin Netanyahu and Defense Minister Benny Gantz.

Netanyahu requested that the security cabinet meet for the first time in two months to discuss Iran next Sunday as tensions with Tehran rise.

While attending an Independence Day event on Sunday, Netanyahu said, "The struggle against Iran and its proxies and the Iranian armament efforts is a huge mission."