A MASSIVE explosion and fire rocked a port in southern Iran at the weekend, purportedly linked to a shipment of a chemical ingredient used to make missile propellant, killing 25 people and injuring around 800.

Helicopters and aircraft dumped water onto the raging fire at the Shahid Rajaei port throughout the night and into this morning.

The explosion occurred as representatives of Iran and the United States met on Saturday in Oman for the third round of negotiations over Tehran’s nuclear programme.

No-one in Iran suggested explictly that the explosion had been caused deliberately. However, Iranian Foreign Minister Abbas Araghchi, who led the talks, had acknowledged on Wednesday that “our security services are on high alert, given past instances of attempted sabotage and assassination operations designed to provoke a legitimate response.”

State media reported the casualty figures, saying that the authorities had identified only 10 of the dead, including two women.

Meanwhile, state television reported today that the fire was under control and said it would be fully extinguished soon. It also said that activities had resumed at the port, showing footage of containers of a commercial ship being unloaded.

There were few details on what had sparked the blaze, which reportedly caused other containers to explode, just outside Bandar Abbas.

Private security firm Ambrey says the port had received a missile fuel chemical in March. It was part of a shipment of ammonium perchlorate sent from China to Iran on two vessels that was first reported in January by the Financial Times.

The chemical, used to make solid propellant for rockets, was going to help replenish Iran's missile stocks, which had been depleted by its direct attacks on Israel during the conflict in the Gaza Strip.

“The fire was reportedly the result of improper handling of a shipment of solid fuel intended for use in Iranian ballistic missiles,” Ambrey said.

Today, Iranian Defence Ministry spokesman General Reza Talaeinik denied reports that missile fuel had been imported through the port.

“No sort of imported and exporting consignment for fuel or military application was [or] is in the site of the port,” he told state TV by phone. He dismissed foreign reports on the missile fuel as baseless.