Stephane Dujarric, a spokesman for the UN Secretary-General, said the organization has no way of "knowing for sure whether this is true or not."
At the same time, the UN called on all parties to avoid "actions that could lead to miscalculations and escalation of the conflict, which has already become very destructive," TASS reports.
Earlier, Dmitry Polyansky, First Deputy Permanent Representative of Russia to the UN, said that the Russian side would send a letter to the Secretary General of the United Nations António Guterres against the background of information that appeared about the risk of using a “dirty bomb” by Kyiv.