The U.S. Secretary of State said Russia is "ultimately" responsible for chlorine gas attacks allegedly carried out by Syria against rebel-held suburbs in Damascus earlier this month.
The Syrian and Russian governments have rejected accusations of involvement in the use of chemical weapons, according to reports.
Syria's Foreign Ministry branded the accusations "lies and allegations" on Wednesday, state-run media outlet SANA reported.
Meanwhile, Russian Deputy Foreign Minister Sergei Ryabkov told Interfax agency that whenever peace efforts advance, the United States promotes "rigged, unverified reports" of chemical weapons attacks.
On Tuesday, U.S. Secretary of State Rex Tillerson said Russia is "ultimately" responsible for chlorine gas attacks allegedly perpetrated by the Syrian government against the rebel-held Damascus suburb of Eastern Ghouta earlier this month.
After a Paris meeting where diplomats from 29 countries gathered to plan sanctions against the Syrian government, Tillerson claimed that "whoever conducted the attacks, Russia ultimately bears responsibility for the victims in East Ghouta and countless other Syrians targeted with chemical weapons."
Ministers from France, Germany and Turkey were among those who launched the International Partnership Against Impunity for Use of Chemical Weapons on Tuesday.
The Paris meeting took place less than a week after the Turkish government launched a military operation against the Syrian Democratic Forces in northern Syria, a mainly Kurdish group that led the resistance against Islamic State forces in Syria. The attack constitutes an open violation of Syrian sovereignty.
The United States and France have urged the Turkish government to show restraint in its military incursion, but have so far stopped short of taking direct action to prevent such action. The Syrian Observatory for Human Rights has reported 18 civilian deaths as a result of Ankara's attacks.