Hundreds of Iranian schoolgirls targeted in mystery poisonings as supreme leader urges death penalty for "unforgivable crime"

Iran's supreme leader said Monday that if a series of mysterious poisonings at girls' schools are proven to be deliberate, the culprits should be sentenced to death for committing an "unforgivable crime."

It was the first time Supreme Leader Ayatollah Ali Khamenei, who has the final say on all matters of state, has spoken publicly about the suspected poisonings, which began late last year and have sickened hundreds of children.

Iranian officials only acknowledged them in recent weeks and have provided no details on who may be behind the attacks or what chemicals - if any - have been used. Unlike neighboring Afghanistan, Iran has no history of religious extremists targeting women's education.