This is the horrifying moment a huge explosion rips through a port in Iran, leaving at least six killed and more than 700 injured.

Unbelievable videos shared on social media show black billowing smoke 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 sitting miles away from the epicenter of the explosion.

Authorities have give no cause for the unbelievable explosion yet.

Iranian state TV however has specifically ruled out any energy infrastructure as causing - or being damaged - in the explosion.