More than 1,000 female children have been reportedly poisoned since 25 November, 2022, in Iran.
The act has been described by the supreme leader of the country, Ayatollah Ali Khamenei as an “unforgivable” crime which should be punished by death, if deliberate.
Iran state TV reported amid public anger over a wave of suspected attacks in schools.
Over 1,000 schoolgirls have suffered poisoning since November, according to state media and officials, with some politicians blaming religious groups opposed to girls’ education.
The poisonings have come at a critical time for Iran’s clerical rulers after months of protests since the death of a young woman held by police for flouting hijab rules.
“Authorities should seriously pursue the issue of students’ poisoning,” Ayatollah Ali Khamenei was quoted as saying by state TV.
“If it is proven deliberate, those perpetrators of this unforgivable crime should be sentenced to capital punishment.”
The poisonings began in November in the holy Shi’ite Muslim city of Qom and spread to 25 of Iran’s 31 provinces, prompting some parents to take children out of school and protest.
Authorities have accused the Islamic Republic’s “enemies” of using the attacks to undermine the clerical establishment. But suspicions have fallen on hardline groups operating as self-declared guardians of their interpretation of Islam.
Interior minister Ahmad Vahidi said at the weekend that “suspicious samples” had been gathered but urged people to stay calm.
He said at least 52 schools across the country had been affected and claimed unnamed enemies of the republic were trying to incite fear.
At least one boys’ school in the western city of Borujerd has also been affected, state media reported.
No details have been given on which chemicals may have been used or exactly who could be responsible, but officials have said test results will be published “as soon as possible”.
Pictures of girls wearing oxygen masks and connected to intravenous drips have sparked protests in some cities, including the capital Tehran, with anger also directed at Iran’s Revolutionary Guard.
The children affected have reportedly complained of heart palpitations, dizziness, headaches, lethargy and feeling unable to move – but so far no one has died.
Some described smelling tangerines, chlorine or cleaning products.
Schoolgirls were among those who took part in the wave of anti-government demonstrations last year over the death in police custody of 22-year-old Mahsa Amini.
Some were pictured removing their headscarves, tearing up pictures of the Ayatollah and calling for his death.
It has been suggested the apparent poisonings could be a form of revenge for that activism or a more general attack on girls’ education.
In 2014, people took to the streets of the city of Isfahan after a wave of acid attacks, which appeared to be aimed at terrorising women who violated the strict Islamic dress code.