Syrian government forces have attacked rebel-held areas with poisonous chlorine gas in recent weeks and months, leaving men, women and children coughing, choking and gasping for breath, according to Associated Press news agency interviews with more than a dozen activists, medics and residents on the opposition side.
Syria flatly denied the allegations, and they have yet to be confirmed by any foreign country or international organization. But if true, they highlight the limitations of the global effort to rid President Bashar al-Assad's government of its chemical weapons.
Witnesses near Damascus and in a central rebel-held village told the AP of dozens of cases of choking, fainting and other afflictions from inhaling fumes that some said were yellowish and smelled like chlorine cleanser.
Some of those interviewed said they believe the gas was responsible for at least two deaths.
They said the fumes came from hand grenades and helicopter-dropped barrel bombs, which are crude containers packed with explosives and shrapnel.
The UN Security Council called for an investigation Wednesday. Council members expressed "grave concern" over the allegations, said Nigeria's UN Ambassador U. Joy Ogwu, council president.
It's an accusation that carries high stakes, and the Syrian opposition has an interest in pushing such claims in hopes of spurring the world to take stern action against Assad, who has been locked in a civil war for three years and faces a Sunday deadline for handing over all his chemical weapons for destruction.