MOSCOW — Russia sharply criticized the new United Nations report on Syria’s chemical arms use on Wednesday as biased and incomplete, hardening the Kremlin’s defense of the Syrian government even while pressing ahead with a plan to disarm its arsenal of the internationally banned weapons.

The Russians also escalated their critiques of Western governments’ interpretations of the report, which offered the first independent confirmation of a large chemical weapons assault on Aug. 21 on the outskirts of Syria’s capital, Damascus, that asphyxiated hundreds of civilians.

Although the report did not assign blame for that assault to either side in Syria’s civil war, analyses of some of the evidence it presented point directly at elite military forces loyal to Syria’s president, Bashar al-Assad. The United States, Britain, France and human rights and nonproliferation groups also say that the report’s detailed annexes on the types of weapons used, the large volume of poison gas they carried, and their trajectories lead to the conclusion that the forces of Mr. Assad were culpable.

The Russian criticism came as the United Nations Security Council’s five permanent members began a second day of talks on a draft resolution aimed at ensuring that the Syrian government honors its commitment to identify and surrender all chemical munitions for destruction, steps it officially agreed to take under a deal negotiated Saturday by Russia and the United States that averted a punitive American missile strike on Syria.