Separatist rockets streaked across hills in eastern Ukraine on Monday as rebels pounded the positions of Ukrainian government troops holding a strategic rail town while both sides pressed ahead with mobilizing more forces for combat.
Kiev's military said five more Ukrainian soldiers were killed in clashes while municipal authorities in the big rebel-controlled city of Donetsk said 15 civilians were killed at the weekend by shelling in a surge of violence on Saturday following the collapse of a new peace effort.
Talks between Ukraine, Russia and rebel officials in Minsk had raised hopes of a new cease-fire to stem the violence in a conflict which has claimed more than 5,000 lives. But they broke up without progress with Ukraine and with the separatists accusing each other of sabotaging the meeting.
Donetsk reverberated to the thud of artillery and mortar fire through the night and several homes were destroyed with at least one civilian death on Monday.
But separatists kept up attacks on Debaltseve, a strategic rail hub to the northeast of Donetsk, in an attempt to dislodge government forces there.
The outskirts of Yenakieve and Vuhlegirsk, both on the main highway to Debaltseve, were under heavy artillery fire as rebel multiple rocket launchers and artillery pummelled the positions of Ukrainian troops in the area.
At one point, a salvo of around three dozen rockets fired from rebel positions screamed across surrounding hills towards Debaltseve. It was followed 15 minutes later by incoming fire from government forces.
"The toughest situation is around Debaltseve where the illegal armed formations are continuing to storm the positions of Ukrainian military," military spokesman Andriy Lutsenko told a briefing. But he said Ukraine's forces in the town were enough to hold it and he denied government forces were encircled.
German Chancellor Angela Merkel appealed for a cease-fire to be urgently restored in Ukraine, under the terms of the Minsk peace plan, and said Germany would not support Kiev's military forces through deliveries of weapons.
The New York Times reported on Sunday that President Barack Obama's administration was however taking a new look at providing Ukrainian forces with defensive weapons and equipment in the face of the rebel offensive.