In reporting to the Security Council, UN General Secretary Ban Ki-Moon said the attack in Syria was the "most significant" use of chemical weapons since 1988.
He said: "This is the most significant, confirmed use of chemical weapons against civilians since Saddam Hussein used them in 1988."
"After two and a half years of tragedy, now is the moment for Security Council to uphold its political and moral responsibilities."
While the UN confirmed that sarin was used in a chemical weapons attack, conventional weapons are still destroying families in Syria.
The UN Secretary General has said there is "overwhelming and indisputable" evidence that chemical weapons were used in an attack in Syria.