A Ukrainian official said Russia used "chemical aerosol munition with suffocating effect" on troops.
Shershen said the chemical used was a banned one, but he did not give further details.
Shershen did not identify the gas, nor say if any Ukrainian or Russian troops were affected.
Marinka, which is around 80 miles from Bakhmut, has been the scene of intense fighting between Russian and Ukrainian forces, and photos published in March show it has largely been reduced to a wasteland.
But in his comments, Shershen said that Ukrainian forces are still fighting there, as the country tries to push back against Russia with its long-awaited counteroffensive.
Persons:
Valeriy Shershen, Shershen, —, Suspilne
Organizations:
Service, Russian, Joint Press Center, Tavria Defense Force, Kyiv Post, The New, Pravda, Suspilne, Politico, Russia
Locations:
Russia, Ukraine, Ukrainian, Marinka, Ukraine's, Donetsk, Bakhmut