A bombing attack in southern Iran claimed by the Islamic State group has killed 91 people, state media said Saturday, raising an earlier toll after two victims had succumbed to wounds.

The two blasts in Kerman on Wednesday hit crowds at a memorial ceremony near the tomb of Qasem Soleimani, a top Revolutionary Guards general killed in a US drone strike in Iraq in January 2020.

"The death toll from the terrorist incident reached 91 after two people, including a child, hospitalised in intensive care, succumbed to their injuries," official news agency IRNA quoted a local health official as saying.

The attack is the deadliest in Iran since 1978, when arson killed more than 370 people trapped in a cinema in Abadan, in the country's southwest, according to archives.

Islamic State (IS) group jihadists on Thursday claimed responsibility for the blasts. A statement said two of IS members had "activated their explosive belts" in the middle of "a large gathering of apostates, near the grave of their leader".

The Iranian intelligence ministry said on Friday that "one of the suicide bombers" was "of Tajik nationality", while the identity of the second attacker has not yet been established.

At least 11 suspects have been arrested across six Iranian provinces over the attack, the ministry said.

The funerals of the victims took place on Saturday in Kerman with the participation of Iranian President Ebrahim Raisi and General Hossein Salami, head of the Islamic Revolutionary Guard Corps.

Soleimani was head of the Guards' foreign operations arm, the Quds Force, before his death. He is celebrated in his country for his role in the fight against IS in neighbouring Iraq as well as in Syria