A massive explosion tore through Iran’s largest commercial port on Saturday, killing at least 25 people and wounding nearly 800 others, according to state media.

The blast occurred at Shahid Rajaei Port in southern Iran’s Bandar Abbas city near the Strait of Hormuz, through which a fifth of the world’s oil output passes.

The port’s customs office said in a statement carried by state television that the explosion probably resulted from a fire that broke out at the hazardous and chemical materials storage depot.

Images from the official news agency IRNA showed rescuers and survivors walking along a wide boulevard carpeted with debris after the blast at Shahid Rajaei, more than 1,000km (620 miles) south of Tehran.

Flames engulfed a truck trailer and blood stained the side of a crushed car, while a helicopter dropped water on massive black smoke clouds billowing from behind stacked shipping containers.

Citing local emergency services, state TV reported that “hundreds have been transferred to nearby medical centres”, while the provincial blood transfusion centre issued a call for donations.

The explosion came several months after one of Iran’s deadliest work accidents in years. The coal mine blast in September, caused by a gas leak, killed more than 50 people at Tabas in the east of the country.

Saturday’s explosion came amid high-level Iran-US talks in Oman on Tehran’s nuclear programme, with both sides reporting progress.