A fire and a massive explosion rocked a port in southern Iran on Saturday, injuring at least 516 people, state television reported.

The blast happened at the Rajaei port just outside of Bandar Abbas, a major facility for container shipments for the Islamic Republic.

Social media videos showed black billowing smoke after the blast.

Authorities have offered no cause for the explosion yet.

Mehrdad Hasanzadeh, a provincial disaster management official, told Iranian state television there were injuries in the blast, without elaborating. He added that first responders were trying to reach the area while others were attempting to evacuate the site.

Hasanzadeh said the blast came from containers at Rajaei port in the city.

Rajaei port mainly handles container traffic and also has oil tanks and other petrochemical facilities. (AP/AFP)