Rebel fighters take part in a training session in the northeastern city of Deir Ezzor.

The Syrian regime used chlorine gas, a lethal chemical agent, against Islamic State of Iraq and Syria (ISIS) fighters to halt them from advancing towards its key air base in the eastern city of Deir Ezzor, a monitoring group reported on Saturday.

The Syrian Observatory for Human Rights said on its website that ISIS stopped advancing in the military air base after “heavy shelling and bombardment by the regime forces.”

The Observatory added that it received “confirmed reports of suffocation cases in ISIS that the regime forces used the Chlorine gas during the bombardment.”

“ISIS pulled back from areas in the mount of Deir Ezzor after it was exposed to regime’s heavy bombardment,” the London-based monitor said.

It also reported that 68 jihadists were killed during the past three days including two French citizens, one Tunisian and 33 Syrians.

However, it described clashes as “continuing between the two sides in al-Huwayqa neighborhood” in the province.

Earlier, the Syrian regime was on the defense when trying to withstand heavy ISIS attacks in the air base. It lost 19 soldiers when a suicide bomber blew himself up in a booby- trapped vehicle overnight near its airbase, the monitor reported Saturday.

ISIS fighters control most of Deir Ezzor province, but half of its capital remains in government hands.

The oil-rich province lies between ISIS-controlled Raqa province and the border with Iraq, and is a key prize for the jihadist group which declared an Islamic “caliphate” straddling the two countries in June

If inhaled, chlorine gas – a deadly agent widely used in World War One – turns to hydrochloric acid in the lungs, which can lead to internal burning and drowning through a reactionary release of water in the lungs.

So far, Damascus has handed over 1,300 metric tonnes of toxic chemicals but not yet destroyed a series of underground bunkers and hangars used to produce and store its deadly stockpile.

In early December, Washington urged for closer monitoring of the long-delayed destruction of Syria’s dozen chemical weapons production facilities, which is several months behind schedule.

 
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