Blood stains a road in Chahbahar, Iran, where two suicide bombers blew themselves up and killed at least 28 people on Wednesday. ((Press TV/Associated Press) )

Two suicide bombers blew themselves up near a mosque in southeastern Iran on Wednesday, killing at least 39 people at a Shia mourning ceremony, state media reported.

The attack, which also injured 90, took place outside the Imam Hussein Mosque in the port city of Chahbahar, near the border with Pakistan, the official IRNA news agency said.

The bombers targeted a group of worshippers at a mourning ceremony a day before Ashoura, which commemorates the seventh-century death of the Prophet Muhammad's grandson. Hussein is one of Shia Islam's most beloved saints.

An armed Sunni militant group called Jundallah, or Soldiers of God, claimed responsibility in a statement posted on its website.

The group has carried out sporadic attacks in Iran's southeast to fight alleged discrimination against the area's Sunni minority in overwhelmingly Shia Iran.

The group said Wednesday's attack was a second act of revenge for the execution of its leader, Abdulmalik Rigi, in June.

(CBC)

"This operation is a warning to the Iranian regime that it must end its interference in the religious affairs of the Sunnis, stop executions and release the prisoners," said the internet statement.

"Otherwise, martyrdom operations will continue with a stronger force."

One of the attackers detonated a bomb outside the mosque and the other struck from inside a crowd of worshippers, state TV reported.

Security forces shot one of them, but the bomber was still able to detonate the explosives, the report said, quoting deputy Interior Minister Ali Abdollahi. A third attacker was arrested, state TV said.

Forensic official Fariborz Ayati put the number of dead at 39 and said they included women, children and a newborn baby, IRNA reported.