Russia on Wednesday said its forces had strengthened their position on the frontline near Avdiivka, a day after Ukraine warned Moscow was stepping up strikes to encircle the eastern town.
Avdiivka is symbolically and strategically important to Kyiv, lying just north of the Moscow-controlled city of Donetsk which was seized by separatist forces in 2014.
It has since become a symbol of Ukrainian resistance against Moscow, with Kyiv clinging on there despite relentless Russian attacks during the Kremlin's almost 20-month-long offensive.
"Actions from the southern group of forces supported by aviation, artillery fire and heavy flamethrower systems, improved the situation along the front line in the vicinity of Avdiivka," the Russian Defense Ministry said.
Local Ukrainian officials on Tuesday told AFP that Moscow's forces had launched an artillery attack on the town in the morning and were firing incessantly.
"Battles continued throughout the night" in the north and south of the town, the head of the town's administration Vitaliy Barabash said Wednesday.
Barabash said Ukrainian troops were "most likely finishing" repelling Russian forces.
Ukrainian officials were "engaged in persuading people to evacuate every day," he said.
Ukraine's armed forces said Russian forces had "intensified actions" in several areas including Avdiivka.
"Our defenders repelled all enemy attacks and prevented the loss of lines and positions," military spokesman Andriy Kovalyov said.