Ukrainian forces have retaken more than 3,000 square kilometers of territory from Russian forces since the beginning of September, the General Staff of the Armed Forces of Ukraine revealed in a Facebook post on Sunday.

"In the Kharkiv direction, we began to advance not only to the south and east, but also to the north. There are 50 kilometers to go to the state border (with Russia)," it added.

There has been no response from the Russian side.