PARIS (AP) — Russia is ultimately to blame for any use of chemical weapons in Syria, U.S. Secretary of State Rex Tillerson said Tuesday amid reports of a suspected chemical attack this week near the capital, Damascus.

Tillerson said Russia is violating a 2013 agreement it made with the U.S. on the removal of chemical weapons from Syria and is helping the Syrian government breach the Chemical Weapons Convention, which bans their use.

The secretary of state said Russia must stop vetoing U.N. Security Council resolutions on holding those who use such weapons accountable. If it cannot support a future Security Council resolution to that end, it should abstain, Tillerson said.

"There is simply no denying that Russia, by shielding its Syrian ally, has breached its commitments to the United States as a framework guarantor" of the 2013 agreement, Tillerson said.

"Russia's failure to resolve the chemical weapons issue in Syria calls into question its relevance to the resolution of the overall crisis. At a bare minimum, Russia must stop vetoing and at least abstain on future UNSC resolutions on this issue," he said.

Tillerson spoke in Paris, where the U.S., France and 22 other countries launched a new organization aimed at identifying and punishing anyone who uses chemical weapons.

The group plans to publish information about chemical attacks to name and shame perpetrators and eventually sanction them. U.N. efforts to punish perpetrators in Syria have failed, repeatedly blocked by Russia.

Activists and rescue teams said the Syrian government launched an attack Monday with suspected poisonous gas that affected nearly 20 civilians in a rebel-held suburb near Damascus. The Syrian government denies using chemical weapons; Russia says extremists have used chemical weapons in the past.

French Foreign Minister Jean-Yves Le Drian said, "Those who carry out chemical weapons attacks need to be made aware that we know who they are, and we will go after them."

The French government announced Tuesday that it is freezing the assets of companies that help furnish material to the Syrian Scientific Studies and Research Center, a Syrian lab accused of producing chemical weapons. France says affiliated companies based in multiple countries have been furnishing materials for the manufacture of chemical weapons, including sarin gas.