Updated

Russia's U.N. ambassador says the expert body that has determined responsibility for chemical weapons attacks in Syria "is dead" but Moscow is ready to discuss "a new mechanism."

Vassily Nebenzia told reporters after a closed Security Council discussion Wednesday that the Joint Investigative Mechanism, or JIM, "has discredited itself completely."

Russia vetoed two council resolutions last week to keep the JIM in operation, and this week it rejected a third Swedish-Uruguayan draft resolution to revive the joint U.N.-Organization for the Prohibition of Chemical Weapons investigative body before it was put to a vote.

At the heart of the dispute is Russia's demand for major changes in the way the JIM operates, and the insistence of the U.S. and 10 other council members that its independence and operation remain unchanged.