Two bombs exploded near the mausoleum of Iranian commander Qasem Soleimani on the fourth anniversary of his assassination by the US, according to Iran’s state TV.
Hundreds of people were injured when bombs exploded near the Saheb al-Zaman mosque in Kerman.
Videos showed bodies on the side of the road and ambulances racing to the site.
Ayatollah Ali Khamenei, Iran’s Supreme Leader, pledged that the “terrorist attack” will be dealt with a “harsh response.”
There were no early claims of responsibility from any groups for what is thought to be Iran’s deadliest such attack in 42 years.
However, Arab separatists and Sunni jihadist groups such as the Islamic State (IS) have claimed responsibility for recent attacks on security personnel and Shia shrines in the country.
Before being murdered in a US drone attack in nearby Iraq in 2020, Soleimani was regarded as Iran’s most powerful figure after the supreme leader.
The attack on Wednesday comes amid rising regional tensions after the deputy head of the Iran-backed Palestinian party Hamas was assassinated in an apparent Israeli drone strike in Lebanon.
When the explosions occurred, enormous people were taking part in a procession down a road adorned with banners glorifying Qasem Soleimani, according to footage shown by Iranian official TV.
In a video footage following one of the explosions, people can be heard shouting and then seen fleeing in fear.
According to Iranian media, the first device went off about 15:00 local time (11:30 GMT), around 700m (2,300ft) from the Garden of Martyrs cemetery outside the Saheb al-Zaman mosque on Kerman’s eastern fringes.
They said the second attack occurred approximately 15 minutes later, around 1km away from the cemetery, and targeted individuals who had escaped the first.
The governor of Kerman province told official news agency Irna that both explosions occurred outside security checkpoints and that police were certain they were caused by bombs. However, he stated that it was unclear if they were detonated remotely or by suicide attackers.
According to the hardline Tasnim news agency, which is connected with Iran’s Revolutionary Guards, “two bags carrying bombs” were presumably detonated “by remote control.”
“We were walking towards the cemetery when a car stopped suddenly behind us and a waste bin containing a bomb exploded,” a witness told Isna news agency.
“We only heard the sound of the explosion and saw people falling.”
According to the local emergency services organisation, the bombs killed 103 individuals and injured another 211. They further stated that several of the injured were in critical condition.
According to the Iranian Red Crescent, among the dead was at least one paramedic who was dispatched to the scene of the first explosion and was hit by the second.
The second blast, according to Interior Minister Ahmad Vahid, killed and injured the most people, and an investigation has been initiated to uncover who was behind the incident.
