Ukraine’s Volodymyr Zelensky has accused Russia of “craziness” as they attempt to capture the eastern town of Bakhmut.
Severe fighting is taking place in the area surrounding the town in the Donetsk region, which has been targeted by the Russians for months.
Ukrainian forces are poised to advance on the strategic southern key city of Kherson, but attacks in the eastern region are continuing in force, Mr Zelensky said.
Taking Bakhmut, which sits on a main road leading to the Ukrainian-held cities of Sloviansk and Kramatorsk, would be a symbolic victory for Russia. It had a pre-war population of about 70,000.
"This is where the craziness of the Russian command is most evident,” he said in his nightly address.
“Day after day, for months, they are driving people to their deaths there, concentrating the highest level of artillery strikes.”
Mr Zelensky did not mention the looming battle for Kherson, which analysts say could prove pivotal and determine whether Ukraine can loosen Russia’s grip on the south.
He said in a video address that there would be good news from the front, but did not give details.
Russian appointed officials in the Kherson region said its forces had rebased to the left bank of the Dnipro river as it prepares for fighting.
Ukrainian soldiers said Russian shelling was stepping up again after having tailed off in recent weeks.
“They have good defensive lines with deep trenches, and they are sitting deep underground," Vitalii, a Ukrainian soldier near the frontline, told Reuters.
Ukrainian forces dramatically advanced along the Dnipro earlier this month, but progress appears to have slowed amid Russian reinforcements.
Oleksii Reznikov, Ukraine’s defence minister, said wet weather and rough terrain were making Kyiv’s counter-offensive in Kherson harder than it was in the northeast, where it pushed Russia back in September.
As Russia began losing ground in a counter-offensive starting in September, Putin has intensified the conflict, partially mobilising Russian reservists and threatening the use of nuclear weapons to defend Russia.
His forces have recently launched a new campaign of strikes using missiles and Iranian-made drones to strike against Ukraine’s energy infrastructure.
Russia has continued to “terrorise" the Kyiv region, launching several attacks on Wednesday night, governor Oleksiy Kuleba said.
“The elimination of the fire and the consequences of the attack is ongoing," he said, adding there were no casualties.
