Judiciary spokesman Alireza Jamshidi today said the accused don't have employment links with education.
The Defenders of Human Rights Center of Nobel Peace Prize laureate Shirin Ebadi condemned the arrests and called on authorities to give a positive response to the demands of the teachers' union.
Radio Farda reports that on March 12 three teachers were arrested in the Western city of Kermanshah.
The reason for their arrest or the charges they face have not been announced.
In recent months Iranian teachers have staged several protests over salaries and working conditions.
(with material from AFP)