An Iranian airliner was forced to return to a southern airport minutes after takeoff when a homemade bomb was found aboard, state television said, in an incident a security official called a "sabotage operation."

The report said the bomb was found in a toilet but gave no other details on the device. The incident took place late May 30.

As Iran prepares for its June 12 presidential election, there have been a number of violent incidents. A bombing May 28 at a mosque in the southern city of Zahedan killed 25 people and wounded 80. A day later, a shooting at Iranian President Mahmoud Ahmadinejad's campaign office in the same city injured three people.

The plane to Tehran, carrying 140 passengers, returned to an airport in the southwestern city of Ahvaz 15 minutes after takeoff after a passenger reported a suspicious package. The plane belongs to one of Iran's commercial airlines, Kish Air.

A news Web site, YaariNews, which is close to former President Mohammad Khatami, said Khatami was planning to come back to Tehran from Ahvaz about the same time, but he changed his schedule and departed earlier.

It was unclear whether Khatami ever intended to travel on the Kish Air flight.