Update : Five dead and more than 700 injured in blast at Iran port

The suspected chemical blast took place at Shahid Rajaee, the country's largest commercial port, near the southern city of Bandar Abbas on Saturday morning.

The explosion blew out windows and roofs of nearby buildings and destroyed cars. Residents reported feeling the impact of the blast up to 50km (31 miles) away.

Videos online show a fire growing into a huge inferno before the explosion, with people subsequently fleeing the blast and others lying wounded on the roads, surrounded by smoking debris.

Authorities had dispatched helicopter crews to try and douse the flames, while medical crews rushed to transport the injured to hospitals.

Some workers were "still trapped under collapsed roofs and "we are trying to rescue them", one official told local media according to BBC Persian.

Pictures also showed survivors on roads littered with twisted metal scraps and rubble