Ukraine sent more than 100 Russian soldiers 'to Hell' in a coordinated strike on the frontlines in the battle for the control of Soledar, its military has claimed.
In a statement, the military said the soldiers "went together to Hell" after they were struck by missiles.
Soledar has been the centre of Russian aggression in recent days as it lies north of the strategically important city of Bakhmut.
Yevgeny Prigozhin, head of the Wagner mercenary group and a close ally of Russian President Vladimir Putin, said his forces had captured all of Soledar and killed about 500 Ukrainian soldiers after heavy fighting.
Both Russia's and Ukraine's military say the fight is still ongoing.
Prigozhin said: "The whole city is littered with the corpses of Ukrainian soldiers."
The brutality of the fighting in the area has been widely commented on by the Ukrainians.
Ukrainian President Volodymyr Zelenskyy said on Monday: "Everything is completely destroyed. There is almost no life left."
He added: "The whole land near Soledar is covered with the corpses of the occupiers and scars from the strikes.
"This is what madness looks like."
Ukraine’s deputy defence minister, Hanna Malyar, said earlier this week Russia has thrown "a large number of storm groups" into the fight for the city.
Read more: Ukraine's Bakhmut: Inside the frontline city
"The enemy is advancing literally on the bodies of their own soldiers and is massively using artillery, rocket launchers and mortars, hitting their own troops."
Donetsk governor Pavlo Kyrylenko told Ukrainian state TV that 559 civilians remain in Soledar, including 15 children, and it was impossible to evacuate them due to ongoing fighting. The town had a pre-war population of around 10,500.
In a statement on Facebook, the Ukrainian military general staff said Russian forces were suffering heavy losses as they tried to take Soledar and sever Ukrainian supply lines.
Russia has struggled to cement control over the town, which would be Russia's most substantial gain since August after a series of retreats before Ukrainian counter-offensives in the east and south.
Earlier this week Russia appointed Chief of the General Staff Valery Gerasimov as overall commander for what Moscow calls its "special military operation" in Ukraine, now in its 11th month.
The change effectively demoted General Sergei Surovikin, who was appointed only in October to lead the invasion and oversaw heavy attacks on Ukraine's energy infrastructure.
Surovikin was ordered to head the campaign after Ukrainian offensives turned the tide of the war and drew attention to poor training, equipment and morale among Russian forces.
If pro-Russian forces succeed in taking Soledar, it would be a stepping stone in Moscow's thrust to capture Ukraine's eastern Donbas industrial region.
The town would be a base to attack the nearby city of Bakhmut, a supply line hub in eastern Ukraine, where defenders have held out for months.