Positions on both sides are "changing dynamically" along the eastern front as fighting there has "somewhat escalated," a Ukrainian official said.
"There are fierce battles, and the positions of the parties are changing dynamically several times a day," Ukraine's Deputy Defense Minister Hanna Maliar said Sunday.
Russia has been "actively advancing" near the city of Kupyansk in the country's northeastern Kharkiv region for two days in a row, Maliar said. "We are on the defense," she added.
Further south along the eastern front, Maliar said Ukrainian forces are gradually moving forward around Bakhmut and that there are "daily advances on the southern flank" of the long-contested city.
On Bakhmut's northern flank, Ukrainian forces are trying to hold their positions, while Russian forces continue to attack, Maliar said.
"In Bakhmut itself, we are shelling the enemy, and the enemy is shelling us," she added.
And south of Bakhmut, Russian forces are also on the offensive in areas surrounding the towns of Avdiivka and Marinka, Maliar said.
"Our defenders continue to effectively hold them back. Hot battles continue with no change in positions," she said.
It is not possible for CNN to immediately verify claims of territorial gains or losses by either side.
Here are the areas each side controls in southern and eastern Ukraine: