Russian forces shelled more than 40 towns in Ukraine's eastern Donbass region, the country's military has said, threatening to close off the last major escape route for civilians caught in the path of its invasion, which has already exceeded the third month.

After failing to take the Ukrainian capital, kyiv, or its second city, Kharkov, Russia tries to gain full control of the Donbass, made up of two eastern provinces that Moscow claims on behalf of the separatists.

Russia has deployed thousands of troops to the region, attacking from three sides in an attempt to encircle Ukrainian forces holding out in the city of Severodonetsk and its twin Lisichansk.

Its fall would leave the entire Luhansk province under Russian control, a key war objective of the Kremlin.

“The occupiers shelled more than 40 towns in the Donetsk and Luhansk region, destroying or damaging 47 civilian sites, including 38 homes and a school. As a result of this shelling, five civilians were killed and 12 wounded," the Joint Task Force of the Ukrainian armed forces said on Facebook.

The statement indicates that 10 enemy attacks were repelled, four tanks and four drones were destroyed and 62 “enemy soldiers” were killed.

Ukrainian President Volodymyr Zelensky said Russian troops "vastly outnumber us" in some parts of the east.