A massive explosion and subsequent fire rocked Iran’s Shahid Rajaei port in the south of the country on Saturday, reportedly linked to a chemical shipment used in missile propellants.

The blast claimed the lives of four people and left more than 500 injured, AP reports.

The incident unfolded as Iranian and US officials met in Oman for the third round of discussions concerning Tehran’s fast-advancing nuclear programme.

While Iranian authorities did not directly suggest the explosion resulted from an attack, Foreign Minister Abbas Araghchi, leading Iran’s negotiation team, noted on Wednesday, “Our security services are on high alert given past instances of attempted sabotage and assassination operations designed to provoke a legitimate response.”

Chemical shipment tied to missile fuel

For hours after the blast, Iranian officials provided little clarity regarding the cause, only stating that the explosion was unrelated to the nation’s oil sector.

At least 281 people injured in Iran post explosion

However, the private security firm Ambrey reported that the port had received a shipment of “sodium perchlorate rocket fuel” in March.

According to Ambrey, the fuel, reportedly transported from China via two vessels, was intended to replenish Iran’s missile stockpiles following attacks on Israel during the conflict with Hamas in Gaza.

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

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Social media footage from the Shahid Rajaei port explosion on Saturday showed reddish smoke rising before the detonation, indicative of chemical involvement.

Iran’s state-run IRNA news agency reported that the Customs Administration blamed a “stockpile of hazardous goods and chemical materials stored in the port area" for the explosion, without offering further details.

Shahid Rajaei port, a vital hub for Iranian imports and exports, has been targeted previously. In 2020, it suffered a cyberattack attributed to Israel, following Israeli claims of thwarting an Iranian cyber operation against its water infrastructure.