Syria warns 'terror groups' may use chemical arms
Syria warned the United Nations on Saturday that rebels may use chemical weapons after they gained control of a factory producing toxic chlorine east of Aleppo city.
"Terrorist groups may resort to using chemical weapons against the Syrian people... after having gained control of a toxic chlorine factory," the foreign ministry said, adding that Syria would never use chemical weapons.
The statement may be referring to the Syrian-Saudi Chemicals Company (SYSACCO) factory near the town of Safira, which was taken over earlier this week by rebel fighters from the jihadist Al-Nusra Front.

Use as a weapon
World War I
Main article: Poison gas in World War I
Chlorine gas, also known as bertholite, was first used as a weapon in World War I by Germany on April 22, 1915 in the Second Battle of Ypres.[61] As described by the soldiers it had a distinctive smell of a mixture between pepper and pineapple. It also tasted metallic and stung the back of the throat and chest. Chlorine can react with water in the mucosa of the lungs to form hydrochloric acid, an irritant that can be lethal. The damage done by chlorine gas can be prevented by a gas mask, or other filtration method, which makes the overall chance of death by chlorine gas much lower than those of other chemical weapons. It was pioneered by a German scientist later to be a Nobel laureate, Fritz Haber of the Kaiser Wilhelm Institute in Berlin, in collaboration with the German chemical conglomerate IG Farben, who developed methods for discharging chlorine gas against an entrenched enemy. It is alleged that Haber's role in the use of chlorine as a deadly weapon drove his wife, Clara Immerwahr, to suicide.[62] After its first use, chlorine was utilized by both sides as a chemical weapon, but it was soon replaced by the more deadly phosgene and mustard gas.[63]
Iraq War
Main article: 2007 chlorine bombings in Iraq
Chlorine gas has also been used by insurgents against the local population and coalition forces in the Iraq War in the form of chlorine bombs. On March 17, 2007, for example, three chlorine-filled trucks were detonated in the Anbar province killing two and sickening over 350.[64] Other chlorine bomb attacks resulted in higher death tolls, with more than 30 deaths on two separate occasions.[65] Most of the deaths were caused by the force of the explosions rather than the effects of chlorine, since the toxic gas is readily dispersed and diluted in the atmosphere by the blast. The Iraqi authorities have tightened security for elemental chlorine, which is essential for providing safe drinking water for the population.
Assads last warning to rebels before using chemical weapons. West, Israel on high preparedness