The Iranian embassy in Lebanon said the dead man, Hessam Khoshnevis, was in charge of Tehran’s reconstruction assistance in Lebanon. It said he was killed by “armed terrorist groups”, a label used by the Syrian government to describe Assad’s foes, on the road to Lebanon as he returned from Damascus.

A Syrian opposition commander said the attack was carried out by rebel fighters near the Syrian town of Zabadani close to the Lebanese border.

Iran has strongly backed Assad during the uprising in which the United Nations says nearly 70,000 people have been killed. In September Iran’s Revolutionary Guards commander-in-chief said the force was providing non-military support in Syria and may get involved militarily if there is foreign intervention.

Iran’s state-run media claims Khoshnevis was only passing through Syria, not stationed there as some believe, on his way to a civil engineering position in Lebanon where he was allegedly aiding in national reconstruction efforts. Iran is currently blaming the “Zionist enemy” for the death of Khoshnevis’ on Tuesday; however, there has yet to be an individual or group of Syrian rebels to claim credit for the attack. Regardless, the death is almost sure to complicate regional politics, with Iran having previously offered military support to President Bashar al-Assad should any foreign nation attempt to intervene in the country’s approximately two-year-old civil war.