BEIRUT — Diplomats on the U.N. Security Council sparred Wednesday over whether to hold President Bashar Assad’s government responsible for a chemical weapons attack that killed more than 80 people Tuesday in northern Syria, while U.S. intelligence officials, Doctors Without Borders and the U.N. health agency said evidence pointed to nerve gas.

The Trump administration and other world leaders said the Syrian government is to blame, but Moscow, a key ally of Assad, said the assault was caused by a Syrian airstrike that hit a rebel stockpile of chemical arms.

Nikki Haley, the U.S. ambassador to the United Nations, shows pictures of Syrian victims of Tuesday's chemical attack as she addresses a meeting of the Security Council on Wednesday. The council met in an emergency session to consider a resolution to back an investigation and compel the Syrian government to cooperate. Associated Press/Bebeto Matthews

Early U.S. assessments showed the use of chlorine gas and traces of the nerve agent sarin in the attack on the Syrian town of Khan Sheikhoun, according to two U.S. officials who weren’t authorized to speak publicly on the matter and demanded anonymity.

Israeli military intelligence officers also believe Syrian government forces were behind the attack, Israeli defense officials told the Associated Press. Israel believes Assad has tons of chemical weapons, despite a concerted operation three years ago by the Organization for the Prohibition of Chemical Weapons to rid the government of its stockpile, said the officials, who spoke on condition of anonymity because they weren’t authorized to brief the media. Turkish President Recep Tayyip Erdogan also blamed the Syrian government for the attack.

In Khan Sheikhoun, rescue workers found terrified survivors still hiding in shelters as another wave of airstrikes battered the town Wednesday. Those strikes appeared to deliver only conventional weapons.

Among those discovered alive were two women and a boy found hiding in a shelter beneath their home, the Civil Defense search and rescue group told the AP.

The effects of the attack overwhelmed hospitals around the town, leading paramedics to send patients to medical facilities across rebel-held areas in northern Syria, as well as to Turkey. The Turkish Health Ministry said three victims died receiving treatment inside its borders. The Britain-based Syrian Observatory for Human Rights monitoring group put the toll at 86 killed.

Victims of the attack showed signs of nerve gas exposure, the World Health Organization and Doctors Without Borders said, including suffocation, foaming at the mouth, convulsions, constricted pupils and involuntary defecation. Paramedics used fire hoses to wash the chemicals from the bodies of victims.

Medical teams also reported smelling bleach on survivors of the attack, suggesting chlorine gas was also used, Doctors Without Borders said.

The magnitude of the attack was reflected in the images of the dead – children piled in heaps for burial, a father carrying his lifeless young twins.

The visuals from the scene were reminiscent of a 2013 nerve gas attack on the suburbs of Damascus that left hundreds dead and prompted an agreement brokered by the U.S. and Russia to disarm Assad’s chemical stockpile. Western nations blamed government forces for that attack, where effects were concentrated on opposition-held areas.

At the Vatican, Pope Francis said during his general audience that he was “watching with horror at the latest events in Syria,” and that he “strongly deplored the unacceptable massacre.”

Tuesday’s attack happened just 60 miles from the Turkish border, and the Turkish government – a close ally of Syrian rebels – set up a decontamination center at a border crossing in the province of Hatay, where the victims were initially treated before being moved to hospitals.

At the United Nations, U.S. Ambassador Nikki Haley warned that the Trump administration will take action if the Security Council does not in response to the attack.

The council was convened in an emergency session to consider a resolution that would back an investigation by the chemical weapons watchdog and compel the Syrian government to cooperate with a probe. It was drafted by the U.S., Britain and France.

Syria’s government denied it carried out any chemical attack on Khan Sheikhoun. Russia’s Defense Ministry said the toxic agents were released when a Syrian airstrike hit a rebel chemical weapons arsenal and munitions factory on the town’s eastern outskirts.

British Ambassador Matthew Rycroft dismissed that account, saying the U.K. had seen nothing that would suggest rebels “have the sort of chemical weapons that are consistent with the symptoms that we saw yesterday.”

Diplomats were also meeting in Brussels for a major donors’ conference on the future of Syria and the region. Representatives from 70 countries were present.

A top Syrian rebel representative said he holds U.N. mediator Staffan De Mistura “personally responsible” for the attack. Mohammad Alloush, the rebels’ chief negotiator at U.N.-mediated talks with the Syrian government, said the envoy must begin labeling the Syrian government as responsible for killing civilians. He said the U.N.’s silence “legitimizes” the strategy.

“The true solution for Syria is to put Bashar Assad, the chemical weapons user, in court, and not at the negotiations table,” said Alloush, who is an official in the Islam Army rebel faction.

Syria’s rebels, and the Islam Army in particular, are also accused of human rights abuses in Syria, but rights watchdogs attribute the overwhelming portion of civilian causalities over the course of the six-year war to the actions of government forces and their allies.

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