UN chief Antonio Guterres on Thursday urged the Security Council to revive efforts to punish those responsible for chemical weapons use in Syria.
The use of chemical weapons in Syria's nearly seven-year war "seriously challenges the global taboo against these weapons of mass destruction," Guterres told the Security Council meeting on confidence-building measures to tackle the proliferation of weapons of mass destruction.
"If the use of chemical weapons in Syria is once again determined, the international community needs to find an appropriate way to identify those responsible and hold them to account," he said.
Guterres opened the meeting warning that the threat from weapons of mass destruction "seems to be gathering force."
Russia used its veto power twice in November to block the renewal of a UN investigative panel tasked with identifying those responsible for chemical attacks in Syria.
A month earlier, the panel had released a report that found the Syrian air force had dropped sarin on the rebel-held village of Khan Sheikhoun in April, killing scores of people.
The Joint Investigative Mechanism (JIM), set up by Russia and the United States in 2015, shut down in November but Western powers have kept up efforts to restore some sort of mechanism for accountability.
US Ambassador Nikki Haley told the council that Russia stood in the way of international action to hold Bashar Assad’s regime accountable, and said the top UN body "must respond to this outrageous violation of international law."
But Russian Foreign Minister Sergei Lavrov accused the US and some other Western nations of "advancing baseless accusations against Damascus."
France will host an international meeting in Paris on Tuesday on boosting cooperation against "unacceptable impunity in the use of chemical weapons," French Ambassador Francois Delattre said.
The Organization for the Prohibition of Chemical Weapons (OPCW) continues to present to the council reports from its fact-finding missions in Syria.
A recent OPCW report concluded that sarin was used in another incident on March 30 in the village of Latamneh and is currently before the council.