TEHRAN: A suicide bomber blew himself up at a Shia religious procession in the Iranian city of Chabahar on Wednesday killing at least 39 people in an attack claimed by Sunni rebel group Jundallah.

A pathologist cited by the official IRNA news agency said 38 bodies had been brought to the town's mortuary from what is the deadliest attack against Shia ceremonies, among them women and children. A 39th casualty later succumbed to his wounds, the pathologist said.

The bomber struck in a central square where worshippers were taking part in a procession marking the eve of the last day of Ashura, Red Crescent official Mahmoud Mozafar told the ILNA news agency.

“An individual walked up to some Red Crescent ambulances and blew himself up,” he said.

The governor of Sistan-Baluchestan province, Ali Mohammad Azad, said: “Two terrorists were killed, one in the explosion and the second by police.”The prefect of Chabahar, Ali Bateni, said a third “terrorist” was later arrested. An intelligence official said he was arrested near the border while attempting to leave the country.

“There were two terrorists who were spotted before they carried out their attack but one of them managed to detonate his explosive vest,” Bateni told IRNA.

“The ringleader of this terrorist action has been arrested.”The attack came on the eve of the final day of Ashura, one of the high points of the Shia calendar when large crowds of worshippers gather in mosques across predominantly Shia Iran.

But unlike most of the rest of the country, Sistan-Baluchestan where Chabahar is situated has a significant Sunni community and has seen persistent unrest in recent years by the Sunni militants of Jundallah (Soldiers of God).

The group claimed Wednesday's attack, saying it was to avenge the hanging of their leader Abdolmalek Rigi. It identified the two militants as Saiful Rahman Chabahari and Hessan Khashi.

“This operation was a revenge for the hanging of the head of the movement Abdolmalek and other members of Jundallah,” the group said on its website.

“In this suicide operation in the city of Chabahar, tens of guards (members of the elite Revolutionary Guards) and mercenaries have been killed. The operation was carried out to expose the aggressors in Baluchestan.”

Jundallah, which says it is fighting for the rights of the province's large Sunni ethnic Baluchi community, has claimed many deadly attacks on Iranian security forces over the past decade as well as assaults that have led to civilian deaths.

British Foreign Office minister Alistair Burt said he was “appalled” to hear about the suicide bombing and said London “strongly condemns this atrocity”.

“I was appalled to hear of today's horrific bomb attack in Iran against pilgrims marking Ashura in the city of Chabahar,” the minister for the Middle East and North Africa said in a statement.

“The UK strongly condemns this atrocity. We deplore terrorism in all its forms. Our thoughts are with all those injured and their families.”

Jordan's King Abdullah II condemned the “terrorist” suicide bombing, while United Arab Emirates Foreign Minister expressed his country's “full solidarity” with Iran.