New Zealand's United Nations ambassador Jim McLay wants an immediate investigation into a chlorine gas attack in Syria.
Representatives on the Security Council, including Mr McLay, were in tears as they watched a video of doctors trying to save three toddlers caught in the attack, in March.
"Some of the worst stuff I've ever had to watch, I've got to say. There were moments when all I wanted to do was look away, and then I realised that the people we were seeing actually had to live through this, and regrettably they had to die through it," Mr McLay said.
It came 10 days after the Security Council condemned the use of chlorine as a weapon in Syria and threatened to take action if it was used again.
Mr McLay said the Syrian airforce had been blamed for the attack but it was not yet clear who committed the atrocity.
He said the Organisation for the Prohibition of Chemical Weapons had to act swiftly.
"We have insisted that the investigation and the report must be undertaken very quickly because evidence disappears very fast and must be gathered."
Mr McLay said that if the council did not act on this atrocity, then other forces would think they could do this sort of thing with impunity.
"And that would be a deplorable outcome," Mr McLay said.
The head of the Syrian American Medical Society, Zaher Sahloul, briefed reporters after the Council's meeting.
"I can tell you that all members have been affected by the testimonies, and videos that they have seen, some of them cried. I can tell you there is a sense of outrage that this is happening in Syria after the resolution, 2209. I would say the majority of the members ask for accountability."
The Security Council failed last year to refer the civil war in Syria, now in its fifth year, to the International Criminal Court for possible prosecution of war crimes and crimes against humanity. Syrian ally Russia, backed by China, vetoed the move.