China reiterated its opposition to the use of chemical weapons and voiced support for a comprehensive and fair probe into an alleged poison gas attack in Syria during a United Nations Security Council emergency meeting on Monday.

"China supports a comprehensive, objective and impartial investigation that would stand the test of history and facts, with the perpetrators being brought to justice," said Wu Haitao, China's deputy permanent representative to the UN, at the meeting held at UN headquarters in New York.

Staffan de Mistura, the UN special envoy for Syria, said that the recent developments in Syria more than ever before reflect the perils that UN Secretary-General Antonio Guterres has warned about.

"[Dangers] of different Middle East fault lines completely crossing each other and interconnected, of conflicting interests – of both global and regional powers, and forms of escalation that can have absolutely devastating consequences that is difficult for us to even imagine," said de Mistura.

He called on all sides to respect international law and ensure humanitarian access to all people in need, saying "the first priority must be to protect civilians".

The attack on Saturday killed at least 60 people and hurt more than 1,000 at several sites in Douma, a town near the capital Damascus, according to Reuters, which cited the Union of Medical Care Organizations in its reports.

Thomas Markram, deputy UN high representative for disarmament affairs, said that the Organization for Prohibition of Chemical Weapons (OPCW) is gathering information and will report its findings on the alleged attack.

"There is, sadly, little to be said today that has not already been said. The use of chemical weapons is unjustifiable. Those responsible must be held to account," he said.

Wu said China supported the Security Council and OPCW as the main channels for addressing chemical weapons and it hoped that parties concerned would take a constructive approach.

He said a political settlement was the only way to resolve the Syrian question, with the international community respecting Syria's sovereignty, unity and territorial integrity.

Russian Ambassador to the UN Vassily Nebenzia said the US, UK and France were carrying out a deliberate policy to stoke international tensions. Without justification, they were engaged in a confrontational policy against Russia and Syria, prompting others to follow suit, he said.

He said the use of sarin or chlorine in Douma had not been confirmed. He invited those who would dispute the point to proceed from the premise that no chemical attack had taken place.

He said the OPCW experts should immediately fly to Damascus, where Syrian authorities and Russian troops would provide the conditions for them to go to the scene and familiarize themselves with the situation, as called for by the US president and other Western leaders.

US Ambassador to the UN Nikki Haley said what was being considered was not over a dispute between the United States and Russia, but about the use of chemical weapons on civilians.

"There can be no more rationalization about our failure to act," she said.

Haley said the council must re-establish a professional and impartial mechanism to investigate chemical attacks in Syria.

Karen Pierce, British representative to the UN, said there must be an independent fact-finding mission to determine if chemical weapons had been used, and if so, which ones.

She said it must be followed by an independent investigation to determine who was responsible. The Russian Federation's offer for an OPCW visit to Douma was worth pursuing, so long as that organization had full freedom of action and access, she added.

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