Thirteen Ukrainian soldiers and 10 civilians have been killed in the past 24 hours in the country's separatist-minded east, Kiev authorities said, after the collapse of peace talks dimmed hopes of a near-term cease-fire.
The civilian and military death toll has mounted in the past two weeks after rebels launched a new offensive. Hopes of de-escalation evaporated on Saturday with Ukraine's representative and separatist envoys accusing the other of sabotaging negotiations.
The Organization for Security and Co-operation in Europe, which took part in the talks in Minsk, Belarus, along with envoys from Ukraine and Russia, said rebel delegates had not been ready to discuss key points of a peace plan, including enforcement of a cease-fire, and sought to redraw a blueprint agreed last September.
"Their representatives who were present were not in a position to discuss the proposal put forward by the trilateral contact group. In fact, they were not even prepared to discuss implementation of a cease-fire and withdrawal of heavy weapons," the OSCE said in a statement.
It said rebels had instead pushed for a revision of a cease-fire plan, agreed in Minsk last September.
The terms of that 12-point protocol have been repeatedly violated, but Kiev and the international community see it as the only viable roadmap to end the nine-month-long conflict in which over 5,000 people have been killed.
In Moscow, Kremlin spokesman Dmitry Peskov said late on Saturday that it was too early to comment on the Minsk talks.
In eastern Ukraine, the Kiev military reported no let-up in rebel attacks on government positions. "Fighting continues across all sections of the frontline," Kiev military spokesman Volodymyr Polyovy said in a briefing.
Clashes are intense around the town of Debaltseve, he said, referring to a Kiev-held transport hub connecting the two main rebel strongholds that separatists aim to cut off.
"There is no question of encirclement or cutting off of the main communication lines … the situation is under control," he said.
The rebel advance has succeeded in seizing part of nearby Vuhlehirsk from Kiev troops, Polyovy said. On Sunday the town was being pounded by near-constant shelling, a Reuters witness reported.
The Interior Ministry said on Sunday a further seven civilians had been killed in shelling on Sunday of Debaltseve, while the Luhansk regional administration said three civilians had been killed in shelling across the region overnight.
Residents are being encouraged to abandon the areas of fiercest fighting, where many have been living in makeshift bomb shelters, waiting for breaks in the bombardment to make quick trips for food and water.
In Kiev-controlled Slovyansk, refugees arrived in buses from Debaltseve and other frontline towns.
Pensioner Vyacheslav Gurov said half of his town of Avdiivka had been completely destroyed. "We don't even know who's shooting. Both the rebels and the national guard are at it ... there's no water, no electricity, no heating, nothing," he said.
In the rebel stronghold of Donetsk, a witness saw the body of a young man stretched out on a street in the city center, killed when a shell struck a wall nearby.
Nadezhda Petrovna, 68, a neighbor, said the man was trying to run away from the attack when a shell landed in front of him.
"It is like this every day, people are getting killed, we are sleeping fully dressed so we can run into the cellar, this is becoming unbearable," she said.
Following the collapse of Saturday's talks, there was no word on when fresh negotiations might take place.