Iranian security officials defused a bomb planted on a domestic passenger plane, officials said on Sunday, the latest incident of violence ahead of next month's presidential election. The attempted bomb attack occurred on Saturday on a Kish Air flight headed to Tehran from the oil-rich western city of Ahvaz near the border with Iraq, the Fars news agency reported. "Last night, 15 minutes after the plane with 131 passengers took off, flight security guards found a handmade bomb placed in the lavatory," Fars said. "The plane landed immediately at Ahvaz airport and the bomb was defused." The incident occurred just two days after 25 people were killed in a powerful bomb attack on a mosque in Zahedan in southeastern Iran claimed by a shadowy Sunni rebel group.