The General Staff of the Ukrainian Armed Forces says fierce fighting is taking place in the eastern strongholds of Bakhmut and Maryinka, APA reports citing Reuters.
It stressed that Ukrainians are repelling the enemy.
Meanwhile, Ukrainian media say Russia on Sunday destroyed a church in the southern region of Zaporizhzhia with an S300 surface-to-air missile.
Footag shows people moving religious paintings out of the church whose roof and walls were heavily damaged.
The leader of the Wagner Group private military firm, Yevgeny Prigozhin, said at least 100 Ukrainian prisoners of war were released on Sunday.
Footage shows people who appear to be Ukrainian troops walking in line supported by fellow soldiers and being carried on stretchers.
Andriy Yermak, the head of Ukraine's Presidential Office, said on social media on Sunday that 130 Ukrainians had returned home.
Ukrainian Deputy Defence Minister Hanna Maliar also said 2,235 prisoners of war has returned home since Russia-Ukraine war began.