In a statement late Saturday, the ministry revealed that those arrested included individuals with “hostile motives” who sought to “instill terror” in students and shut down schools.
The ministry also suggested a possible link to the terrorist Mujahedeen Khalq Organization (MKO).
“Fortunately, from the middle of last week until today, the number of incidents in schools has decreased significantly and there have been no reports of sick students,” it added.
Since late November, schoolgirls have suffered fainting, nausea, shortness of breath and other symptoms after reporting “unpleasant” odors in schools, with some being treated in hospitals.
The suspected poison attacks sparked fear and anger among pupils and their parents.
The arrests were made in provinces including Tehran, Qom, Gilan, Khorasan Razavi, West Azarbaijan, East Azarbaijan, Zanjan, Kurdestan, Hamedan, Khuzestan, and Fars. Last Monday, Iran’s Leader Ayatollah Seyyed Ali Khamenei called for the perpetrators of the “unforgivable crime” to be tracked down “without mercy”.