BEIRUT (AP) — A top Syrian rebel representative says he holds U.N. mediator Staffan De Mistura “personally responsible” for the suspected chemical weapons attack that killed more than 70 people in northern Syria one day ago.

Mohammad Alloush, the rebels’ chief negotiator at U.N.-mediated talks with the Syrian government, said the U.N.’s Special Envoy for Syria’s must begin labeling the Syrian government as responsible for killing civilians. He said U.N.’s silence “legitimizes” the strategy.

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

Syria’s rebels, and the Islam Army in particular, are also accused of killing civilians 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.

A proposed U.N. Security Council resolution would condemn the use of chemical weapons in Syria and stress the government’s obligation to provide information about air operations on Tuesday when a suspected chemical attack killed dozens of people.

The resolution drafted by Britain, France and the United States would also stress Syria’s requirement to give investigators the names of those in command of any helicopter squadrons on April 4.

And it calls for immediate access for investigators to air bases where attacks involving chemical weapons may have been launched.

Sponsors were hoping for a vote as early as Wednesday afternoon on the draft resolution.

The Security Council was holding an emergency meeting on the suspected attack in Syria’s rebel-held Idlib province, one of the deadliest in the six-year civil war.

The Russian Foreign Ministry says it opposes a Western draft U.N. resolution condemning a chemical attack in Syria.

The ministry spokeswoman, Maria Zakharova, said Wednesday the draft blames the Syrian government for Tuesday’s attack without any credible investigation.

Zakharova said that video and photo evidence of the attack presented by volunteer first responders could have been fabricated. She blamed the West for staging a “political show” and called for an international probe.