By Michelle Nichols
UNITED NATIONS (Reuters) - The U.N. Security Council has given an international inquiry five more weeks to complete its report on who is to blame for toxic gas attacks in Syria as U.N. chief Ban Ki-moon, France, Britain and others push for those responsible to be punished.
The inquiry was due to submit its report this week, but Ban told the 15-member council in a letter, seen by Reuters on Thursday, that the inquiry needed extra time and wanted to delay its deadline until Oct. 21. The council has extended its mandate until Oct. 31.
In its most recent report to the Security Council last month, the joint United Nations and Organization for the Prohibition of Chemical Weapons (OPCW) inquiry said that Syrian government troops were responsible for two toxic gas attacks and Islamic State militants used sulfur mustard gas.
France, Britain and other council members want the body to act after receiving the next report, the inquiry's fourth.
"There have been two incidents documented by the UN/OPCW of the dropping of chlorine gas. How can we sit by and let that happen? Burning, blistering, barbaric chlorine gas being dropped on innocent people," British Foreign Secretary Boris Johnson told a Security Council meeting on Syria on Wednesday.
As the inquiry works to complete its report, it has identified two Syrian Air Force helicopter squadrons and two other military units it holds responsible for chlorine gas attacks, a Western diplomat told Reuters.
Some diplomats worry that the council could respond weakly or that the issue could be sidelined as the United States and Russia try to salvage a truce deal in Syria.
"Justice demands that no crime is left ignored even as an exchange for a truce," French Foreign Minister Jean-Marc Ayrault told the council meeting during the annual U.N. gathering of world leaders.
"It is up to the Security Council to act under Chapter 7 to condemn these attacks and sanction perpetrators. It is a moral duty and an obligation for the international community which wanted to ban chemical weapons," he said.
Chapter 7 deals with sanctions and authorization of military force by the Security Council. The body would need to adopt another resolution to impose targeted sanctions - a travel ban and asset freeze - on people or entities linked to the attacks
Syria agreed to destroy its chemical weapons in 2013 under a deal brokered by Moscow and Washington. The Security Council backed that deal with a resolution that said in the event of non-compliance, "including unauthorized transfer of chemical weapons, or any use of chemical weapons by anyone" in Syria, it would impose measures under Chapter 7 of the U.N. Charter.
Ban said that if the world did not pursue the perpetrators of brutal crimes in Syria it "would be a grave abdication of duty."
(Additional reporting by John Irish; editing by Stuart Grudgings)