A unilateral ceasefire declared by Russia appears to have had little effect on fighting on the ground, with officials accusing each other of opening fire in several areas.
A Ukrainian rescue worker was killed in a Russian strike, according to Russian state television, and the city of Donetsk was also hit.
Russia declared a 36-hour unilateral cease-fire to coincide with Orthodox Christmas.
Ukraine rejected it, claiming that Moscow might use it to reinforce troops.
Russia’s defense ministry insisted on observing the cease-fire along the entire “line of contact” beginning at 12:00 Moscow time (09:00 GMT) on Friday. It blamed Kiev for continuing to shell Russian positions and settlements in occupied Ukraine.