Both Ukraine and Russia on Sunday reported high casualties in Ukraine's Donbas region, the focus of Moscow's slow, long-running advance into its neighbour's territory.

Much of the fighting in the east has centred on Bakhmut, largely destroyed in months of attacks and shelling by Russia during the year-old conflict.

Ukrainian President Volodymyr Zelenskiy said Russian forces had suffered more than 1,100 dead in less than a week of fighting near the city.

"In less than a week, starting from 6th March, we managed to kill more than 1,100 enemy soldiers in the Bakhmut sector alone, Russia's irreversible loss, right there, near Bakhmut," Zelenskiy said in his nightly video address.

He said Russian forces had also sustained 1,500 "sanitary losses" – soldiers wounded badly enough to keep them out of further action. Dozens of pieces of enemy equipment were destroyed as were more than 10 Russian ammunition depots.

Russia's defence ministry said its forces were conducting further military operations in Donetsk region which, together with adjacent Luhansk region, makes up Donbas.

The ministry said Russian forces had killed more than 220 Ukrainian service members over the past 24 hours.

"In the Donetsk direction... more than 220 Ukrainian servicemen, an infantry fighting vehicle, three armoured fighting vehicles, seven vehicles, as well as a D-30 howitzer were destroyed during the day," the ministry said.

Ukraine said on Saturday that more than 500 Russian troops had been killed or wounded in a recent 24-hour period as they battled for control of Bakhmut.

Reuters could not independently verify the accounts of either side. (Reuters)