Other reports suggest those behind the incidents, seek school closure.
Meanwhile, Iranian President Ebrahim Raisi has instructed his interior minister to get to the bottom of the matter as soon as possible.
President Raisi told Ahmad Vahidi to inform people of the results of the investigation into the incidents in order to dispel concerns among families.
Earlier, Iran’s deputy health minister said the substance used for poisoning the students is not a military chemical agent.
According to Yousef Panahi, the students have been poisoned by chemicals that are available in the market.
An investigation has been launched into the poisonings in the city of Qom and other ones.
An Iranian MP said on Wednesday that 900 students have been so far poisoned.