The Azov Regiment said that Russian occupying troops dropped a poisonous substance of unknown origin from an unmanned aerial vehicle on Ukrainian military and civilians in Mariupol on Monday evening.

"About an hour ago, the Russian occupation troops used a poisonous substance of unknown origin, dropped from an enemy UAV, against Ukrainian military and civilians in the city of Mariupol," the Azov's telegram message says.

Azov also reported that the victims have respiratory failure, vestibulo-atactic syndrome, the consequences of using an unknown substance are being clarified.

In turn, a source close to the Ministry of Defense of Ukraine told the Interfax-Ukraine news agency that "the probability of the Russians using chemical weapons is very high."

At the moment, the Interfax-Ukraine agency does not have confirmation of this information from official sources.