The United Nations Security Council is due to vote on Friday on a U.S.-drafted resolution to condemn the use of chlorine as a weapon in Syria and threaten to take action if such arms are used again in the conflict.
French U.N. Ambassador Francois Delattre, president of the council for March, said on Thursday that he hoped the resolution would be adopted unanimously by the 15-member council. Diplomats said it was unclear how Russia, a Syrian ally, would vote.
The new draft resolution, obtained by Reuters, does not lay blame for previous chlorine attacks in Syria. It "condemns in the strongest terms any use of any toxic chemical, such as chlorine, as a weapon in the Syrian Arab Republic."
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 fluid in the lungs.
The Organisation for the Prohibition of Chemical Weapons (OPCW) has found evidence that chlorine gas was "systematically and repeatedly" used as a weapon in Syria.
The United States, Britain and France accuse the Syrian government of the attacks, which it denies. The Syrian government, meanwhile, blamed rebel groups for using chemical weapons.
The draft resolution "stresses that those individuals responsible for any use of chemicals as weapons, including chlorine or any other toxic chemical, must be held accountable."
Syria agreed in 2013 to destroy its entire chemical weapons program under a deal brokered with the United States and Russia after hundreds of people were killed in a sarin gas attack on the outskirts of the capital, Damascus. Russia supported a U.N. Security Council resolution covering the deal.
Although chlorine is not a prohibited substance, its use as a chemical weapon is prohibited under the 1997 Chemical Weapons Convention, which Syria joined in 2013.