New Delhi/Kyiv, Feb 24 (IANS): The Ukrainian Armed Forces have said that they managed to stop Russian troops in northern Ukraine's Chernihiv region, but heavy fighting is underway in Kharkiv, located in northeast part of the country, where the "enemy" has suffered casualties.

Around 50 Russian troops were killed in Ukraine's "retaliation" to Moscow's military operations, Ukrainian forces said on Thursday in a post on the General Staff's verified Facebook page, claiming that they have shot down six Russian Air Force planes, and two choppers as well as destroying two tanks.

The forces, in a statement, said they regained full control on Mariupol in eastern Ukraine, although the situation in Kherson in the south is said to be critical, where Ukrainian forces are trying to push back the Russian troops.

Meanwhile, more than 50 Ukrainian soldiers had also been reportedly killed and dozens had been wounded in the operations.

Urging citizens to stay calm, the Ukrainian Armed Forces said that all military units are in their positions.