Russian forces in eastern Ukraine fired a banned suffocating chemical gas at Ukrainian troops, a Ukrainian military official said, but the wind ended up blowing it back toward them.

Russians fired a "chemical aerosol munition with suffocating effect on one of the positions," Valeriy Shershen, a spokesperson for the Joint Press Center of the Tavria Defense Force, said, according to Ukrinform's translation. But then "the wind blew in the enemy's direction," he added.

Shershen made the comments on Ukrainian TV, according to Ukrinform, with his comments picked up by other Ukrainian media outlets, including the Kyiv Post, The New Voice of Ukraine, Pravda, and the state broadcaster Suspilne. 

Suspilne and Pravda reported that Shershen claimed the chemical was prohibited.

Shershen did not identify the gas, nor say whether any Ukrainian or Russian troops were affected.

But he did say the incident happened near Marinka, a city in Ukraine's eastern Donetsk region.

Ukraine has previously accused Russia of using banned chemicals as part of its full-scale invasion of the country, which began in February 2022.

This includes claims that Russia used phosphorus — the use of which in civilian areas is a war crime — in the key city of Bakhmut in May and dropped chloropicrin grenades on Ukrainian troops in December.

Top US officials said at the end of last year that they were concerned Russia would use chemical weapons in Ukraine, especially considering the country had previously been accused of poisoning domestic critics, Politico reported in November.

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 showed it had largely been reduced to a wasteland.

Russia said that as of the start of June, it had taken most of the city.

But in his comments, Shershen said that Ukrainian forces were still fighting there as the country tried to push back against Russia with its long-awaited counteroffensive.