Prospects for a criminal trial for Syrian leaders accused of using sarin and other deadly chemicals against civilians appeared to gain momentum Thursday as governments and human-rights groups separately advanced measures seeking justice for victims of poison gas attacks.

At a meeting of the 193-nation Organization for the Prohibition of Chemical Weapons in The Hague, governments overwhelmingly adopted a proposal calling for new restrictions against Syria as well as technical and legal support for prosecuting chemical-weapons offenses anywhere in the world.

The proposal, backed by 69 countries with 45 abstentions, overcame heavy opposition by Russia, which has sought to shield Syrian President Bashar al-Assad from punishment over his government’s repeated use of chemical weapons during the 12-year-old Syrian civil war. Only nine countries joined Russia in opposing the measure. Earlier in the week, OPCW member states voted to block Moscow from taking its customary seat on the watchdog group’s executive council.

As the meeting was underway, a coalition led in part by survivors of Syrian violence unveiled a blueprint for the first international court dedicated entirely to prosecutions of chemical attacks. The plan for an “Exceptional Chemical Weapons Tribunal” is sponsored by 16 human-rights organizations and survivors groups and has drawn the interest of dozens of governments, from Europe and North America and to Asia.

The two-year effort to create a new international tribunal reflects growing frustration over the limited ability of the United Nations and the International Criminal Court to prosecute alleged war crimes, including the use of outlawed chemical weapons. Russia has consistently used its international influence - including its veto power at the U.N. Security Council - to block such cases from moving forward.

Under the proposal, governments could use the new tribunal to prosecute alleged chemical-weapons offenses “where there is no recourse to existing judicial criminal fora, as in Syria,” according to a statement describing the plan. Backers said the blueprint was the product of months of consultations with government officials and legal experts over how to “put an end to impunity,” according to Ibrahim Olabi, a lawyer and founder of the Syrian Legal Development Program, a British nonprofit.

The proposal comes amid efforts by three European nations - France, Germany and Sweden - to unilaterally prosecute Syrian officials over chemical-weapons attacks. French prosecutors earlier this month issued arrest warrants for Assad and other Syrian leaders in connection to one such case.

Syria has been accused of using highly lethal nerve agents and other chemical weapons more than 200 times since 2012, including the 2013 sarin attack in the Damascus suburb of al-Ghouta that killed more than 1,000 people, many of them women and children, according to U.S. estimates. Syria acknowledged possessing hundreds of tons of chemical weapons but has consistently denied involvement in any of the attacks.

The measure adopted by the OPCW on Thursday accuses Syria of failing to account for all of its chemical weapons, which it agreed to destroy in 2013 under an accord brokered by the United States and Russia. It also called for unprecedented restrictions on Syria’s future acquisition of precursor chemicals and equipment that could help the country reconstitute its chemical weapons program.

“To deter future CW use, we must hold those responsible for past use to account,” Mallory Stewart, the State Department’s assistant secretary for arms control, deterrence and stability, told the OPCW gathering. “If we do not do so, other states and non-state actors may turn to using these.”

Thursday’s actions were partly symbolic - supporters say they do not expect Syrian officials to travel outside the country to face charges anytime soon - yet they show the world that the victims of the attacks have not been forgotten, said Gregory Koblentz, director of the Biodefense Graduate Program at George Mason University’s Schar School of Policy and Government.

“Together they demonstrate that, 10 years after the Syrian attack on Ghouta, the international community takes the Syrian chemical threat seriously,” Koblentz said.