Iran Nuclear

This photo released Thursday by the Atomic Energy Organization of Iran, shows a building after it was damaged by a fire, at the Natanz uranium enrichment facility some 200 miles south of the capital Tehran, Iran.

DUBAI, United Arab Emirates | A fire and an explosion struck a centrifuge production plant above Iran’s underground Natanz nuclear enrichment facility early Thursday, analysts said, one of the most-tightly guarded sites in all of the Islamic Republic after earlier acts of sabotage there.

The Atomic Energy Organization of Iran sought to downplay the fire, calling it an “incident” that only affected an under-construction “industrial shed,” spokesman Behrouz Kamalvandi said. However, both Kamalvandi and Iranian nuclear chief Ali Akbar Salehi rushed after the fire to Natanz, a facility earlier targeted by the Stuxnet computer virus and built underground to withstand enemy airstrikes.

The fire threatened to rekindle wider tensions across the Middle East, similar to the escalation in January after a U.S. drone strike killed a top Iranian general in Baghdad and Tehran launched a retaliatory ballistic missile attack targeting American forces in Iraq.

While offering no cause for Thursday’s blaze, Iran’s state-run IRNA news agency published a commentary addressing the possibility of sabotage by enemy nations such as Israel and the U.S. following other recent explosions in the country.

“The Islamic Republic of Iran has so far has tried to prevent intensifying crises and the formation of unpredictable conditions and situations,” the commentary said. But ”the crossing of red lines of the Islamic Republic of Iran by hostile countries, especially the Zionist regime and the U.S., means that strategy ... should be revised.”