What's going on in Iran's schools is deeply sinister - and authorities are trying to hush it up
We have only furtively shot videos and eyewitness testimony.
Iranian authorities allow very few journalists into their country so we cannot investigate or verify. But what is going on in Iran's schools is deeply sinister and worrying.
In one school after another since November students have been victims of what appear to be gas attacks. What kind of gas and the way it is disseminated is impossible to say. Students report the smell of eggs and citrus fruit before becoming overpowered. Some pass out, others are dizzy and nauseous, and many need to go to hospital.
Sky has been handed an interview with one schoolgirl in the Kurdish region of northwest Iran. She described the terrifying moment her classmates realised their school had been targeted.
"The gas attack started from the upper floor and more than half of the 9th graders fell sick and then gradually it spread to the lower floors and they did not let us leave until school time was over, the gas was still there but they did not let us go home."
Making matters worse it seems school authorities and the government have tried to cover up the attacks after they have been carried out.
"A few of us told the principal that our friends are sick and they are in a bad state. But they said you are just acting and lying and nothing has happened to you. Then our own friends called the emergency services and three ambulances arrived and they said it is true what the pupils say."
Sky was passed the interview by a human rights group operating in Iran. It also provided an interview with a mother of a nine-year-old caught in another alleged attack also in the northwest of the country.
"The children and teachers were struggling to get out of the class our eyes were burning, we felt that our faces were burning, the children were all panicking and screaming and pouring into the corridors then the principal called the ambulance and several students and two of the teachers were taken to hospital."
And again how authorities tried to hush it up.
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"The security forces arrived at the school and ordered the personnel and the teachers not to talk about the attack and should say the smell of the gas and the poisoning of the students was because of a burst in the central heating pipes if someone asked."
The country's supreme leader Ayatollah Khamenei has condemned the attacks as unforgivable. But that will leave many unconvinced.
Iran is one of the most tightly controlled countries in the world. Multifarious security agencies maintain a firm grip on society. It is hard to believe that a nationwide campaign of gas attacks on schools has happened without the knowledge of at least some in the government.
Some have claimed the attacks are the work of religious extremists. Militants were blamed for similar attacks in neighbouring Afghanistan. But it seems inconceivable for that to happen on such a large scale below the radar of regime surveillance in a country like Iran.
We can only speculate. Factions in the government may be exacting revenge on schoolgirls who have taken a prominent role in the unrest that has rocked the country for months now.
The government may be trying to shut down schools that have been much of the focus of much of the discontent. Or it may be trying to heighten a sense of terror hoping that too will crush the spirit of discontent.
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Iran was already gripped by fear in the wake of months of repression and unrest. Thousands have reportedly been arrested, tortured and disappeared. Their government has lost all credibility in the eyes of millions but has used brute force to maintain its trip on power.
Iranians must now cope with what appears to be a concerted effort to poison their children.