Russia traded accusations with the United States and Britain at the United Nations on Tuesday over the possibility of a chemical weapons attack in Ukraine, but none produced any evidence to back their concerns.
The comments were made by diplomats to reporters after Russia raised the issue of an ammonia leak in Ukraine's besieged northeastern city of Sumy - blaming "Ukrainian radical nationalist groups" - during a closed-door U.N. Security Council meeting. The accusation was rejected by Britain and the United States.
