TEHRAN, Iran - Suicide bombers killed at least 39 people and wounded dozens Wednesday while targeting a procession of worshipers observing an important Shiite Muslim holiday in southeastern Iran, state media reported.

The Jundallah organization, an extremist Sunni group that claims to represent Iran's mostly Sunni ethnic Baluch minority, posted on a website that it was responsible for the attack. The bombing was the latest sign that the troubles in South Asia, including Sunni extremism, are increasingly seeping into Iran.

Television footage showed bloodstained asphalt in the city of Chabahar's Farmandari Square as panicked crowds rushed to the site of the blast and emergency-response personnel loaded the injured into ambulances.

Initial reports described at least one blast outside the Hossein Mosque and another one or two failed bombing attempts. Shortly after the attack, Jundallah posted photos of two smiling young men, identified as Seif Rahman Chabahar and Hassan Khasi, wearing what appeared to be explosives-laden belts.

"Today two brave warrior offspring of Baluchistan carried out two operations against the governor and dozens of mercenaries of the Revolutionary Guard," said the statement on the website.

Three suspected bombers were killed, and one was arrested.

Jundallah and the Iranian government are locked in a war that has claimed the lives of hundreds of people during the last five years. The eventual death toll from Wednesday's bombing could surpass an Oct. 18, 2009, attack, also claimed by Jundallah, that killed 42 in the city of Pisheen. That was Iran's deadliest internal attack in 20 years.

The Iranian government has accused the United States of supporting Jundallah, an assertion denied by U.S. officials and the extremist group. Washington placed Jundallah on its list of terrorist organizations last month.

But after the bombing, Iran repeated assertions that the attack had been carried out by Jundallah with American and Arab support.

"The perpetrators of these attacks are the Wahabi and Salafist detractors of the revolution of Imam Hossein and those standing behind them, such as the United States and the United Kingdom," Iranian lawmaker Kazem Jalali said, referring to Saudi Arabia, which practices the strict interpretation of Islam known as Salafism.

Jundallah has warned that it is planning retaliatory strikes against the United States in Afghanistan and Pakistan after Washington's decision last month to blacklist the group.

The attacks coincided with Ashura, the annual Shiite religious holiday commemorating the seventh-century slaying of Imam Hossein, grandson of the prophet Muhammad.