The United States circulated a draft U.N. resolution Thursday aimed at identifying the perpetrators of chemical weapons attacks in Syria.

The United States has been promoting Security Council action to assess blame for an increasing number of alleged chlorine attacks, and Russia's U.N. Ambassador Vitaly Churkin said last month that the council should look at the best way to ensure that the people allegedly responsible for chlorine attacks are brought to justice.

The Organization for the Prohibition of Chemical Weapons, the global chemical weapons watchdog based in The Hague, Netherlands, has a mandate to carry out fact-finding missions and has condemned the use of chlorine in Syria as a breach of international law.

But neither the OPCW nor the United Nations have a mandate to determine responsibility for the use of chemical weapons.

U.S. Ambassador Samantha Power said in a statement that "given the frequent allegations of chlorine attacks in Syria, and the absence of any international body to identify the perpetrators of chemical weapons attacks, it is critical that the U.N. Security Council find consensus and set up an independent investigative mechanism."

Russia's deputy U.N. ambassador Vladimir Safronkov said the United States circulated the draft resolution at a closed council meeting on Syria's chemical weapons.

A Security Council diplomat said the resolution would establish a "Joint Investigative Mechanism" that would enable the U.N. to build on the OPCW's expertise and fact-finding missions and conduct investigations to identify those involved in the use of chemical weapons in Syria. The diplomat spoke on condition of anonymity because the draft hasn't been released publicly.

While Russia and the United States have failed to agree on a way to end the Syrian conflict, now in its fifth year, they have agreed in the past on eliminating its chemical weapons stockpile.

Following a chemical weapon attack on a Damascus suburb that killed hundreds of civilians on Aug. 21, 2013 a U.S.-Russian agreement led to a Security Council resolution the following month ordering the destruction of Syria's chemical weapons, precursors, and the equipment to produce the deadly agents.

The Syrian government's support for the resolution and decision to join the OPCW warded off possible U.S. military strikes in the aftermath of the Aug. 21 attack, which Damascus denied carrying out.

While Syria's declared stockpile of 1,300 metric tons of chemicals has been destroyed, there are still outstanding questions about possible undeclared chemical weapons that the OPCW is still investigating.

Chlorine is not a banned agent used in chemical weapons, like sarin or ricin. But it is toxic and its use in attacks in Syria started being reported last year.

In March, the Security Council approved a U.S.-drafted resolution that condemns the use of toxic chemicals such as chlorine in Syria, and threatening militarily enforced action in the case of further violations.