US Ambassador Nikki Haley accused Russia of protecting Syrian President Bashar Assad from responsibility for what she said were multiple chlorine gas attacks on civilians in recent weeks.
Haley told the UN Security Council on Monday that Russia has delayed adoption of a council statement condemning the use of chemical weapons, including a reported chlorine gas attack Thursday in the opposition-held Damascus suburb of eastern Ghouta that injured over 20 civilians including children.
Russian Ambassador Vassily Nebenzia retorted, "It's completely clear to us the goal is to basically accuse the Syrian government of chemical weapons use where no perpetrators have been identified."
Russia proposed a rival press statement eliminating references to Thursday's attack and to "the unacceptable level of violence in Syria, particularly in eastern Ghouta."
He proposed adding language about a new investigative body to determine responsibility for chemical attacks that is unacceptable to the US and its allies.
The US and Russia have been lashing out at each other for months over the issue of accountability for chemical attacks in Syria, which is a close ally of Moscow, reports the Associated Press.
A joint investigation team comprising experts from the UN and the Organisation for the Prohibition of Chemical Weapons concluded that the Syrian government used chlorine gas in at least two attacks in 2014 and 2015 and used the nerve agent sarin in an aerial attack on Khan Sheikhoun last April 4 that killed about 100 people and affected about 200 others.
The team also accused the Islamic State extremist group of using mustard gas in 2015 and again in September 2016 in Um Hosh in Aleppo.
Russia accepted the accusation against the IS militants but rejected the experts' findings on the Syria government as unproven and demanded major changes in the way the expert team from the Joint Investigative Mechanism, or JIM, operates.
The US and about 10 other council members insisted that the JIM must remain independent, but Russia used its veto to prevent its mandate from being renewed.
The result is that there is currently no way to determine responsibility for chemical attacks in Syria.
Haley said the Assad regime must immediately stop using chemical weapons.
Haley stressed that like the JIM, a new mechanism must be independent, impartial and be "controlled by experts, not politicians or diplomats."
She again rejected Moscow's proposed resolution to replace the JIM, saying it ignores the JIM's findings - "an investigation that Russia supported until the investigators found the Assad regime to be responsible."
Russia also wants "to cherry pick investigators" and give the Security Council power to review the findings and decide what goes into the final report, Haley said.