A series of explosions at an Iranian port left at least 28 people dead and hundreds injured on Saturday.

The blasts triggered a vast fire, with thick black smoke billowing into the skies above the coastal facility.

The explosions have killed 28 people and injured 800, according to Iranian emergency services, with officials warning the casualty count may rise.

The first explosion happened at 12.10pm local time at Shahid Rajaee Port in Bandar Abbas, 1,000 kilometres south of Tehran, the capital.

“The explosion occurred in a part of the Shahid Rajaee Port dock, and we are extinguishing the fire,” Esmaeil Malekizadeh, a regional port official, told state television.

Mohammad Ashouri, the local governor, described the blast as “massive” while acknowledging the cause remained unclear.

“For now, our focus is to control and extinguish the fire and there will be an investigation after that,” he said.