Yuriy Bova, mayor of the Ukrainian city Trostianets, said “remains” of chemical weapons were found after Russian troops withdrew. In a video, Bova described how the citizens of the area and neighboring villages sensed a “sweet taste in their mouths” which scared many into leaving.

Ukrainian President Volodymyr Zelensky also said Russia was using “banned phosphorous” materials as chemical weapons against Ukrainians in the war. Bova said officials found the clear and odorless substance sari and other chemical substances.

“We found the remains of chemical weapons in the village of Bilka—sarin and other substances. We discovered ampoules. The Security Service of Ukraine is currently working on this,” Bova said in remarks published Saturday by the National News Agency of Ukraine. “It is possible that the occupiers wanted to use this chemical to strike Kyiv, Poltava or other cities.”

Last week a Ukrainian battalion posted that the Russian military had used chemical weapons against soldiers in Mariupol. One soldier who said he was injured in the attack of the unknown chemical weapons dropped on troops by a drone reported a “sweet-tasting” white smoke.

Another soldier says he lost his breath and collapsed, having felt “cotton legs.” Western nations are attempting to verify the allegations. The Pentagon said the reports were “deeply concerning” despite not having a concrete answer if the reports were true. The Pentagon added the potential use of chemical weapons is “reflective of concerns that we have had about Russia’s potential to use a variety of riot control agents, including tear gas mixed with chemical agents.”

Ukrainian President Zelensky vowed to investigate all accusation and said if in fact chemical weapons have been used, it would mark a “new stage of terror against Ukraine.”