Russia, Syria's veto-wielding ally on the Security Council, agreed to endorse the measure during a Friday vote. It paves the way for a probe over who is responsible for chemical attacks, a contentious issue and still subject to debate.

While the council cannot hold perpetrators criminally responsible, identifying them will allow for prosecutions in the future.

Samantha Power, US Ambassador to the United Nations, said afterwards that the accountability mechanism adopted by the Security Council will end impunity.

"The joint investigative mechanism will identify you if you gas people," Power said. "Pointing the finger matters."

New deal

To date, a total of 1,300 metric tons of chemical stockpiles have been surrendered by the Syrian government and neutralized by the US Navy.

"What we are trying to do is get beyond the mere finding of the fact that it may have been used and actually find out who used it and designate accountability for its use," US Secretary of State John Kerry told reporters ahead of the vote.

While Russia and the United States have failed to find common ground over the Syrian civil war, now in its fifth year, they have agreed to eliminate Syrian President Bashar al-Assad's cache of chemical weapons.

Following a 2013 sarin attack on a Damascus suburb that sparked a global outcry, Syria agreed to a Washington-Moscow plan to dismantle its chemical weapons capabilities and join an international treaty banning their use.

Rare moment of unanimity over Syria

The final draft of the resolution, obtained by Associated Press, asks UN Secretary-General Ban Ki-moon to convene a panel in coordination with the Organization for the Prohibition of Chemical Weapons.

The panel is to present its first findings to the council after 90 days of work, which is expected to last one year. It is to have "full access" to all locations in Syria and be allowed to interview witnesses and collect materials, according to the draft resolution.

Washington has been pressing for the Security Council to ensure accountability for the growing number of alleged chlorine attacks in Syria, many reportedly using barrel bombs dropped from helicopters.

The US sponsored an informal Security Council meeting in April for council members to hear first-hand accounts of chemical weapons attacks.

In early June, Syrian activists and doctors said chlorine was increasingly being used as a weapon. Separately, reports surfaced that "Islamic State" fighters, who control about a third of Syria and Iraq, used projectile-delivered poison gas against Kurdish forces earlier this summer.

Chlorine is not officially considered a warfare agent and was not among the chemicals declared by Syria, but its use as a weapon is banned by international convention.

jar/bk (AP, Reuters, dpa, AFP)