Ukraine faced relentless Russian attacks on Bakhmut in its eastern Donetsk region, with both sides reporting mounting enemy casualties as they battled across a small river that bisects the ruined town that now marks the front line.
Ukraine's President Volodymyr Zelensky said late on Sunday his forces had killed more than 1,100 Russian soldiers in the past few days as they battled for control of Bakhmut.
"In less than a week, starting from the 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," Zelensky said in his nightly video address.
Russian forces also sustained 1,500 "sanitary losses", soldiers wounded badly enough to keep them out of action, Zelensky said.
Russia's defence ministry said earlier in the day that its forces had killed more than 220 Ukrainian service members over the past 24 hours in the Donetsk direction.
Reuters could not independently verify battlefield reports and neither side gave details of their own casualties.
Ukraine forces control west of the nearly deserted mining town of Bakhmut, while Russia's Wagner mercenary group controls most of the eastern part, with the Bakhmutka River that flows through the town marking the front line, British intelligence said.
Wagner founder Yevgeny Prigozhin said the situation in Bakhmut was "tough, very tough".
"The closer we are to the centre of the city, the harder the fighting... The Ukrainians throw in endless reserves. But we are advancing and we will be advancing," Prigozhin said in an audio statement released by his press service.
He also said members of the Russian army helped his troops with ammunition.
"Yesterday, we got 15 truckloads, today we got 12. And I think we will continue to receive them," he said, adding there was no conflict between his fighters and Russian troops.
Prigozhin had previously complained that Russia's top brass was deliberately starving his men of ammunition, an allegation the defence ministry rejected.
Prigozhin said Wagner "will begin to reboot" and start hiring once Bakhmut is captured. His army has already opened recruitment centres across 42 cities to replenish its ranks.
Waiting for tanks
While Bakhmut's strategic value is debatable, Russia sees capturing it as a step towards a major aim of the war - now in its second year - of seizing all of Ukraine's Donbas industrial region. Donetsk and Luhansk regions make up the Donbas.
Ukraine has decided to stay and fight on in Bakhmut, after initial signs it was planning to withdraw, to grind down Russia's best units ahead of a spring counter-offensive.
Analysts expect a Ukrainian counter-offensive to begin in earnest over April-May when the weather improves and more military aid arrives, including heavy Leopard and Challenger tanks.
Western tanks will significantly change war tactics, Leonid Khoda, a seasoned Ukrainian tank brigade commander who received the Hero of Ukraine award less than a month after Russia's full scale invasion, told Reuters.
"Everyone is waiting, 1st Tank Brigade is waiting too. Not long ago we sent personnel to learn to operate (Leopard) 2A6," said Khoda, who commands the 1st Siversk Tank Brigade which is fighting in the south of Donetsk.
Elsewhere, Russian shelling killed three civilians who were on their way to buy groceries in the southern city of Kherson on Saturday, Zelensky said, denouncing what he called "brutal terrorist attacks" by pro-Moscow units.
Russia has denied targeting civilians.
Ukrainian Foreign Minister Dmytro Kuleba urged Germany in an interview published on Sunday to speed up supplies of ammunition and to start training Ukrainian pilots on Western fighter jets.
Kuleba made clear he did not expect Western allies to give Ukraine the fighter jets it has been asking for any time soon, but said pilots should be ready for when the decision was taken.
Separately, a senior EU official has said the European Union could soon top up the fund used for purchasing weapons for Ukraine by US$3.7 billion (about RM16.6 billion).