She told a news briefing that the number of Russian military units in Ukraine had risen to 280 from 250 a week earlier as Moscow tried to gain the "strategic initiative".
"Fighting is fierce in the Soledar direction," Malyar said. "They (the Russians) are moving over their own corpses."
"Russia is driving its own people to the slaughter by the thousands, but we are holding on," she said.
Another senior military official, Brigadier General Oleksiy Gromov, told the briefing that the military situation in Ukraine remained "difficult", with the heaviest fighting on the eastern front.
Russian forces were trying to cut through Ukrainian lines and surround Ukrainian troops, he said.
Gromov also said the danger of an attack being launched from Belarus, a Russian ally to the north of Ukraine, would remain throughout this year.
(Reporting by Pavel Polityuk, Editing by Timothy Heritage)
