Russia has accused the US of promoting unverified reports about chemical weapons attacks in Syria in order to cloud Moscow’s latest peace initiative.
The Syrian government has also dismissed the reports as “lies”.
The US and 28 other countries are launching a new plan to better identify and punish anyone who uses chemical weapons, amid claims of a suspected gas attack in rebel-held suburbs of Damascus earlier this week.
In an interview with the Interfax news agency, Russia’s deputy foreign minister Sergei Ryabkov accused the US of promoting “rigged, unverified reports” of the alleged use of chemical weapons in Syria to hamper Russian peace efforts.
Mr Ryabkov’s remarks came a day after US secretary of state Rex Tillerson said Moscow “ultimately bears responsibility for the victims” of the latest suspected chemical attack.
The Syrian foreign ministry dismissed the allegations as “unacceptable” and blamed western nations for blocking probes and pressuring investigators after previous attacks.
The US and Russia reached an agreement in 2013 to remove all chemical weapons from Syria, but there have been several reported chemical attacks since then, including one last year that led President Donald Trump to order a retaliatory missile attack on a Syrian air base.
France and the US have urged Turkey to exercise restraint in its offensive on Afrin, where the United Nations says an estimated 5,000 people have been displaced.
Turkish president Recep Tayyip Erdogan said the incursion is progressing “successfully” and will continue until the last “terrorist” is eliminated.
He renewed a threat to extend the offensive east to the city of Manbij, which is also under the control of US-backed Syrian Kurdish fighters. He added that he plans to “foil games along our borders starting from Manbij”, adding that “we will clean our region from this trouble completely”.
Mr Erdogan said that Turkish troops and allied Syrian fighters have killed at least 268 Syrian Kurdish fighters since the operation was launched on January 20. He said Turkish troops have suffered seven or eight losses.
Ankara views the main Syrian Kurdish militia as a threat because of its links to Kurdish insurgents fighting in south-eastern Turkey. The Syrian Kurds are the main US ally against the Islamic State group in Syria, and played a key role in driving the extremists from much of the country’s north-east.
The US has urged Turkey, a Nato ally, to exercise restraint. American troops are based in Kurdish-controlled areas of northern Syria but not in or near Afrin.