In Iran, mourning is turning to anger after a huge blast at its largest commercial port killed at least 40 people and injured more than 1,000.

The explosion happened on Saturday morning at Shahid Rajaee port. Many people rushed to hospitals up and down the country to give blood.

A day later, fires are still blazing as a thick black cloud of toxic chemicals hangs over the surrounding area.

People in nearby towns and cities have been told by the health ministry to stay indoors "until further notice" and wear more protective clothes.

In the nearby southern city of Bandar Abbas, home to the Iranian Navy's main base, all schools and offices were ordered to shut on Sunday to allow authorities to focus on the emergency effort, state TV said.

A local festival not far from Shahid Rajee Port that was supposed to be a celebration spontaneously turned into a solemn occasion for remembering the dead and praying for the injured.

Authorities declared a day of national mourning on Monday, with an additional two days of mourning in Hormozgan province.

It is a reminder that while Iran has been rocked physically by the blast - residents up to 50km (31 miles) away reported feeling the effects - the country is now being rocked by a growing blame game too.

Ambrey Intelligence, a private maritime risk consultancy, said it believed that intense fires that could be seen spreading between containers before the explosion were a result of "improper handling of a shipment of solid fuel intended for use in Iranian ballistic missiles".

The firm said it believed the affected containers had contained solid fuel destined for ballistic missiles, and was aware that an Iran-flagged ship "discharged a shipment of sodium perchlorate rocket fuel at the port in March 2025".

The New York Times quoted a person with ties to Iran's Islamic Revolutionary Guard Corps, speaking on condition of anonymity, as saying that what exploded was sodium perchlorate - a major ingredient in solid fuel for missiles.

Some Iranians are asking whether they should believe speculation on social media which said Iran's military and Revolutionary Guard were storing rocket fuel that they had recently imported from China at the port – a claim which has been denied by an army spokesman.

Many in Iran are blaming the authorities for incompetence and worse, asking: How could so much inflammable material apparently be left on the port without due care?

That is a question that the Iranian regime will need to address. Iranian President Masoud Pezeshkian visited the scene of the explosion on Sunday, saying: "We have come to see first-hand if there is anything or any issue that the government can follow up on."

Pezeshkian had previously ordered an investigation into the cause of the blast, sending the interior minister to the region to lead it.

Defence ministry spokesman Reza Talaei-Nik later told state TV that "there has been no imported or exported cargo for military fuel or military use in the area".

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.

There is also the question of whether Iran's economy may be affected, given the port handles nearly 80% of the country's imports.

On Saturday, authorities were warning of possible food shortages in the near term with the port out of action for some time.

A day later, they were playing that down, saying that the explosion only affected a part of the port and that the rest is functioning normally.

An image from Iran's Tasnim news agency on Sunday showed a helicopter flying through a sky blackened by smoke to drop water on the disaster-struck area, AFP reported.

Others showed firefighters working among toppled and blackened cargo containers, and carrying out the body of a victim. The authorities have closed off roads leading to the site.

The Kremlin said Russian President Vladimir Putin had ordered that multiple specialist firefighting aircraft be sent to Iran to help deal with the aftermath of the disaster.

Beijing's foreign ministry said in a statement to AFP on Sunday that three Chinese victims were in a "stable" condition and that it had received no further reports of casualties.

Among the condolences being sent were from the United Arab Emirates, Saudi Arabia, Pakistan, India, Turkey, the United Nations and Russia.

The explosion ripped through the port as Iranian and US delegations were meeting via mediators in Oman for high-level talks on Tehran's nuclear programme, with both sides reporting progress.

Iran has said it is open to curbs on its nuclear programme in return for sanctions easing but has insisted it will not stop enriching uranium. It insists its nuclear programme is for civilian use.