Six senior Revolutionary Guards commanders have been killed along with 25 other people in a suicide bomb attack in Iran.The attack, on one of the country’s most powerful military institutions has highlighted deepening instability along the Islamic Republic’s south- eastern border. At least 30 other people were injured in the explosion. Witnesses say the suicide bomber detonated explosives strapped to his body outside a conference centre in the south-eastern city of Sarbaz in the Sistan Baluchestan province where many minority Sunnis live. A Sunni rebel group is said to have admitted carrying out the attack. Iranian state television claims the group, called Jundollah, or God’s soldiers, ordered the bombing. Among the dead was General Nourali Shoustari, the chief of the Guards’ ground forces. Iran’s Parliament Speaker paid tribute to the dead Guards officers prompting a chorus of “Death to America” from the floor of the house. The Revolutionary Guard is a branch of the military founded after the Iranian revolution. It is fiercely loyal to President Mahmoud Ahmadinejad and has an estimated 120,000 troops with its own naval and air corps. It also controls the paramilitary Basij militia deployed on the streets of Iran after the disputed presidential election in June when scores of people are believed to have been killed in clashes with security forces during opposition demonstrations as reformist leaders called for a recount amid allegations of widespread election fraud.