Ukrainian border guards said they spotted a Mi-8 helicopter that violated the country's airspace when flew back east, the authority said in a statement published on its website on April 12.

"The border guards revealed a Mi-8, probably Russian, which broke Ukraine's airspace near Stanytsia Luhanska in Luhansk region and than went backwards. An inquiry is holding into this case," the service's spokesman said in a report.

Besides, illegal armed formations continue to use drones to carry an air reconnaissance.

"In all, the Border Service registered 14 drones on the parts the border guards are responsible for," the authority reported.

The Mi-8 is a twin-engine medium utility helicopter that was developed by the Soviet Union and still is in production today by Russia.