An Iranian security official said early on June 8 that the assailants in two deadly attacks in Tehran were Iranian nationals who had joined the Islamic State.
Speaking on Iranian television and quoted by the independent Shargh daily website, Reza Seifollahi, an official in the country's Supreme National Security Council, was asked who were the operatives in the dual attacks that killed 13 people and wounded more than 40.
"About the identity of the attackers, I should say they were from parts of Iran, and had joined Daesh," he said, using a slang term for the extremist Sunni group.
IS had previously claimed responsibility for the attacks, but the Islamic Revolutionary Guard Corps and some top Iranian officials on June 7 had blamed Saudi Arabia and the United States.
It was the first time IS staged a major attack in Iran, which is backing militia groups that are battling IS in both Iraq and Syria. The extremist group considers the 90 percent of Iranians who are Shi'ite Muslims to be apostates.
But the group reportedly has been recruiting from among Iran's sizable Sunni minority population, which resides mostly in restive border areas with Iraq and Pakistan.