What caused the Iranian port blast that killed 40 and injured over 1000?

Iran’s Supreme Leader Ayatollah Ali Khamenei on Sunday ordered a comprehensive investigation into a massive explosion at a key southern port, which killed 40 people and injured more than 1,000.

The directive came after President Masoud Pezeshkian visited the blast site at Shahid Rajaee Port near the Strait of Hormuz, where fires continued to burn over 24 hours after the incident.

"Security and judicial officials must thoroughly investigate, uncover any negligence or intent, and proceed according to regulations," Khamenei said, as quoted by state television.


What Caused the Blast?
The exact cause remains unclear.

The New York Times, citing a source connected to Iran’s Islamic Revolutionary Guard Corps, reported that sodium perchlorate — a chemical used in solid missile fuel — was likely involved.

However, Defence Ministry spokesman Reza Talaei-Nik told state TV there was no imported or exported military fuel at the site.

The port’s customs office suggested the explosion likely started at a hazardous and chemical materials storage facility, while a regional emergency official confirmed that multiple containers exploded.

The explosion comes amid delicate nuclear discussions between Iranian and US delegations in Oman, with both sides reporting progress.

Although Iranian authorities currently regard the blast as accidental, it occurs against the backdrop of long-standing covert conflict with Israel.

The Washington Post previously reported that Israel had conducted a cyberattack on Shahid Rajaee Port in 2020.

Meanwhile, CNN reported that Iranian state media quoted officials blaming a stockpile of hazardous chemical materials for the explosion but did not specify the substances.

Iran’s national oil company confirmed the blast was unrelated to oil refineries, tanks, or pipelines.

Meanwhile, experts told CNN the explosion resembled an ammonium nitrate blast, a chemical widely used as fertilizer and industrial explosives.
Andrea Sella, a chemistry professor at University College London, explained, "Poor storage of ammonium nitrate can dramatically increase explosion risk during a fire. Material ignites and burns fiercely, followed seconds later by a devastating detonation, sending a supersonic shockwave that can shatter windows."