Separatists in east Ukraine said 15 people in territory under their control were killed and over 60 were wounded on Wednesday during battles around the rebel stronghold of Donetsk that is threatening to tip the country back into full-blown war.
Two other deaths were reported in a government-controlled area.
Russian news agencies cited rebel armed forces chief Vladimir Kononov as saying the dead included fighters and civilians. The figure could not immediately be verified.
The Ukrainian government and rebels have accused one another of sparking the latest round of unrest, which marks some of the worst violence since a cease-fire deal was reached in February.
"The Ukrainian side has carried out a provocation and started shelling our positions all along the front," the Interfax news agency quoted Kononov as saying.
Ukrainian military spokesman Andriy Lysenko accused rebels of mounting a major artillery barrage against government-held suburbs west of Donetsk early Wednesday. "The enemy is trying to advance. Ukrainian troops are repelling all attacks and successfully holding onto their positions," Lysenko said.
Russia's Tass news agency quoted the chief physician at the trauma center in Donetsk, Alexander Oprishchenko, as saying his hospital had admitted 60 wounded people for treatment on Wednesday, of whom five were in a grave condition.
Implementation of the cease-fire has foundered as low-intensity battles raged along several points of the 450-kilometer (280-mile) front. Negotiators from the warring sides met for talks in Belarus on Tuesday, but the session concluded without obvious progress.
Reports of casualties among government and separatist fighters have continued unabated, but deaths among noncombatants had almost ceased. That trend has been disrupted in recent days in an indication that the warring sides are again increasingly resorting to indiscriminate shelling.
A man reacts next to a shop which was damaged by the shelling at a local market in Ukraine. (Reuters Photo)
Russia's Interfax news agency cited a rebel representative as saying that one resident in the town of Yenakieve was killed near a waste treatment plant during a 20-minute barrage. Ukraine's military denies it attacked Yenakieve.
The war has killed more than 6,400 people since April 2014.
The Organization for Security and Cooperation in Europe said in its most recent status report that its monitors on Monday heard 109 mainly outgoing explosions from the area around Donetsk airport, which is under rebel control. That neighborhood is around 15 kilometers from Krasnohorivka and Marinka, the suburbs where fighting was unfolding on Wednesday.