US has denied an American-Led airstrike killed hundreds of civilians
The Syrian army said on Wednesday that the airstrike in the eastern Deir al-Zor province hit poison gas supplies belonging to ISIS, and released a toxic substance that killed "hundreds”.
Syrian army officials said it proved that Islamic State and al-Qaeda linked militants "possess chemical weapons".
It also claimed that the air strike, on the village of Hatla, left a white cloud that became yellow as a result of the explosion of a huge store that includes a large amount of "toxic materials”.
The Sana news agency claimed hundreds of people died after being suffocated by the mystery gas.
However, the report could not immediately be independently verified and the US has denied even carrying out a strike.
US Air Force Colonel John Dorrian, a spokesman for the coalition, said it had carried out no air strikes in that area at that time.
Washington blamed the gas attack on President Bashar al-Assad's government
He said: "The Syrian claim is incorrect and likely intentional misinformation."
The United States launched cruise missiles at a Syrian air base last week, in response to a deadly poison gas attack in the west of the country that Washington blamed on President Bashar al-Assad's government.
Syria and its ally Russia deny Damascus carried out any such chemical attack.
Syria launched a deadly poison gas attack in the west of the country
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Moscow has said the poison gas in that incident belonged to rebels.
The US strike on the Syrian air base was the first time Washington has deliberately and directly targeted theSyrian government.
It is separately waging an air campaign against Islamic State in eastern Syria.
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