Two suicide bombers blew themselves up near a mosque in southeastern Iran on Wednesday, killing at least 38 people at a Shiite mourning ceremony, state media reported.
Jundallah, a Sunni Muslim rebel group, claimed responsibility for the attack outside the Imam Hussein Mosque in the port city of Chahbahar, near the border with Pakistan, according to AlArabiya reporter.
The bombers targeted a group of worshippers at a mourning ceremony a day before Ashoura, which commemorates the seventh century death of the Prophet Muhammed's grandson Hussein, one of Shiite Islam's most beloved saints.
The area of Iran is home to armed Sunni Jundallah group, or Soldiers of God, which has waged sporadic attacks to fight alleged discrimination against the area's Sunni minority in overwhelmingly Shiite Iran.
One of the attackers detonated a bomb outside the mosque and the other struck from inside a crowd of worshippers, state TV reported.
Forensic official Fariborz Ayati put the number of dead at 38 and said they included women and children, IRNA reported.
Mahmoud Mozaffar, a senior Iranian Red Crescent Society official, said emergency services had been put on alert over the past few days because of anonymous threats, according to another news agency, ISNA.
In July, two suicide bombers blew themselves up at a mosque in the same province, Sistan-Baluchestan, killing at least 28 people. Jundallah said that attack was revenge for the execution of its leader, Abdulmalik Rigi, in June.
That strike in the provincial capital, Zahedan, also targeted Shiite worshippers during a holiday, the birthday of Hussein, the prophet's grandson.
Iranian officials claim Jundallah, which has operated from bases in Pakistan, receives support from Western powers, including the United States. Washington denies any links to the group, and in November the State Department added Jundallah to a U.S. list of foreign terrorist organizations.
The group has also targeted members of Iran's Revolutionary Guard, the country's most powerful military force.
In its deadliest attack, a suicide bomber hit a meeting between Guard commanders and Shiite and Sunni tribal leaders in the border town of Pishin in October 2009, killing 42 people, including 15 Guard members.
Drug traffickers and smugglers also are active along the barren frontier area of Iran, Pakistan and Afghanistan and have launched attacks on security forces.