THIS is the horrifying moment a huge explosion rips through a port in Iran - killing at least 25 and injuring more than 800.
Shocking videos shared on social media show black smoke billowing into the air after the gargantuan blast as onlookers watch on in horror.
The blast happened at the Rajaei port just outside of Bandar Abbas - a major facility for container shipments for the Islamic Republic that handles roughly 80 million tons of goods a year.
More footage showed glass blown out of buildings miles from the explosion's epicentre.
Iranian state TV said the explosion was likely sparked by a blaze in a depot storing chemicals.
A private maritime risk consultancy said it believed the containers contained fuel for ballistic missiles.
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The fire was the result of “improper handling of a shipment of solid fuel intended for use in Iranian ballistic missiles”, Ambrey Intelligence said.
Disaster management official Mehrdad Hasanzadeh confirmed the blast came from containers at Rajaei port in the city.
State TV reported there had been a building collapse caused by the explosion.
Rajaei port is around 652 miles southeast of the Iranian capital of Iran, on the Strait of Hormuz - the narrow mouth of the Persian Gulf through which 20 per cent of all oil traded passes.
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Industrial accidents happen in Iran, especially because its ageing oil facilities have little access to machinery parts due to strict international sanctions.
The blast happened as Iran and the United States met Saturday in Oman for the third round of negotiations over Tehran's rapidly advancing nuclear program.
US President Donald Trump said on Thursday that an agreement is "well on its way," while Iran scrambled to protect its most important .
The president said: "I think we're doing very well on an agreement with Iran.
"That one is well on its way - we could have a very, very good decision. And a lot of lives will be saved."
But Supreme Leader Ayatollah Ali Khamenei doesn't appear to be taking any chances, as Iran has been found building a ring of steel protection around its nuclear facilities.
Iran is beefing up two deeply buried tunnel complexes - linked to its main nuclear complex - with a massive security perimeter.
Commercial satellite imagery shows defence construction around the base of Mt Kolang Gaz La, located south of the Natanz enrichment complex.
The satellite images, taken on March 29, showed hardened entrances to the complexes, high wall panels erected along the verges of a graded road encircling the mountain peak, and excavations for the installation of more panels.
And the north side of the perimeter joins the Natanz plant security ring, according to a report published by the (ISIS).
The multi-peaked mountain contains a new, large, deeply buried tunnel complex and a separate, smaller one dating back to 2007, which was previously partly destroyed.
Tehran has barred access to the tunnels to inspectors of the UN International Atomic Energy Agency (IAEA) who are monitoring its nuclear program.
And that suggests that Iran is increasingly worried about foreign surveillance of its nuclear production sites, which the regime claims are just for civilian use.
David Albright, the institute president, said the new perimeter suggested that the tunnel complexes - under construction beneath Mount Kolang Gaz La for several years, could become operational relatively soon.
This has raised concerns that they could be used to store Iran's stockpile of highly enriched uranium or undeclared nuclear materials, and advanced centrifuges that could quickly purify enough uranium for a bomb, Albright added.
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IAEA Director General Raphael Grossi said yesterday: "It is obvious that this is a place with numerous and important activities [on Iran's nuclear program].
"It's a bit of a ping pong, but the digging continues, the building continues."