TEHRAN, Iran — A suicide bomber killed five senior commanders of the powerful Revolutionary Guard and at least 37 others Sunday near the Pakistani border in the heartland of a potentially escalating Sunni insurgency, Iranian state news agencies reported.
The attack, which also left dozens wounded, was the most high-profile strike against security forces in an outlaw region of armed tribal groups, drug smugglers and Sunni rebels known as Jundallah, or Soldiers of God.
President Mahmoud Ahmadinejad promised sharp retaliation. But a sweeping offensive by authorities is unlikely.
Iranian officials have been reluctant to open full-scale military operations in the southeastern border zone, fearing it could become a hot spot for sectarian violence with the potential to draw in al-Qaida and Sunni militants from nearby Pakistan and Afghanistan.
The region's top prosecutor, Mohammad Marzieh, was quoted by the semiofficial ISNA news agency as saying Jundallah claimed responsibility for the blast in the Pishin district near the Pakistani border.
There was no immediate statement directly from the group, which has carried out sporadic kidnappings and attacks in recent years — including targeting the Revolutionary Guard — to press their claims of persecution by the Shiite government.
The attack would mark the group's highest-level target. It also raised questions about how the attacker breached security around such a top delegation from the Revolutionary Guard, the country's strongest military force, which is directly linked to the ruling clerics under the supreme leader, Ayatollah Ali Khamenei.
The official Islamic Republic News Agency said the victims included the deputy commander of the Guard's ground forces, Gen. Noor Ali Shooshtari, as well as a chief provincial commander, Rajab Ali Mohammadzadeh. The others killed were Guard members or tribal leaders, it said.
The Revolutionary Guard led the crackdown on dissidents after Ahmadinejad's disputed re-election in June. But the attack Sunday appeared to have no link to the political showdowns.