Dozens of girls from 26 schools in Iran are reportedly being treated for poisoning at hospitals after another wave of apparent toxic gas attacks.
More than 1,000 students have been affected since November. They have suffered respiratory problems, nausea, dizziness and fatigue.
Many Iranians suspect the poisonings are a deliberate attempt to force girls’ schools to close.
Interior Minister Ahmad Vahidi, who has been tasked by the president with finding the “root cause” of the poisonings, on Wednesday dismissed as “false” a report by Fars news agency that three people had been arrested. He also accused foreign-based media and “mercenary groups” of taking advantage of the situation to wage psychological war and worry people.
Some pupils and parents suggested that schoolgirls may have been targeted for taking part in recent anti-government protests.
BBC Persian verified videos showing ambulances arriving at schools and students being treated in hospitals in the capital Tehran, the north-western city of Ardabil and the western city of Kermanshah.
In one from Tehransar, in western Tehran, several girls purportedly from 13 Aban School are seen lying on beds in a hospital ward and receiving oxygen.
Another video from the city’s east shows girls sitting on the pavement outside a primary school. A mother is then seen rushing up to the gate and screaming: “Where is my child?” A man replies: “They’ve poisoned the students with gas.”
Many patients have reported similar symptoms: respiratory problems, nausea, dizziness and fatigue. The first known case was reported at a school in the city of Qom, when 18 schoolgirls fell ill and were taken to hospital on 30 November. Since then, at least 58 schools in eight provinces have been affected, according to local media.
Most cases have involved girls – at both primary and high schools – although there have been some reports of boys and teachers affected.
The BBC has analysed dozens of videos posted to social media and has verified many of the school locations filmed. Many of these show young people in distress in school settings, with some being loaded into ambulances and others lying in hospital beds. Others show ambulances arriving and crowds gathered outside school gates.
Chemical weapons expert Dan Kaszeta, an associate fellow at the Royal United Services Institute (RUSI), said that “finding the alleged causative substance is often the only useful evidence, but can be extremely difficult”. As substances can dissipate or degrade, collecting a sample “pretty much requires you to be there, with the right equipment, at the time of exposure,”
The incidents in Iran have similarities with a series of alleged poisoning cases in Afghan schools in the 2010s, according to Mr Kaszeta. These, he said, were not properly investigated and so remain largely unresolved.
Iranian President Ebrahim Raisi … speaking to a crowd in southern Iran on Friday in a speech carried live on state television, blamed the poisoning on Iran’s enemies.