Russia's State Investigative Committee said it was investigating the suspected use of chemical weapons by Ukrainian forces near the towns of Soledar and Bakhmut.
The Investigative Committee stated that Donetsk, a region loyal to Russia in the territories it controlled in eastern Ukraine, reported the use of chemical weapons by Ukrainian drones near the two cities.
"As a result, Russian soldiers suffer from a deterioration in their health and symptoms of poisoning," the committee added, without providing details or specifying the suspected substance.
Since the start of the military operation nearly a year ago, Russia has repeatedly warned that Ukraine may be preparing to use unconventional weapons, such as biological weapons or a bomb containing radioactive material.
Ukraine and its Western allies rejected these accusations, but they considered it a possible prelude to Russia itself resorting to such methods, but placing the blame on Ukraine, which Moscow considered a mere accusation.