At least 19 soldiers and civilians were killed in clashes across east Ukraine as fierce fighting raged Sunday between government forces and pro-Russian rebels following the collapse of ceasefire talks.
Ukraine's military said that 13 soldiers had died and 20 were wounded over the past 24 hours, pushing the military death toll over the past two days to 28.
Six civilians also died in fighting across the rebels' self-declared Donetsk People's Republic and in Kiev-controlled towns in Lugansk region, government officials and separatists said.  
The latest casualty reports came as Ukraine's two warring sides looked further than ever from agreeing a peace deal after the collapse of truce talks Saturday.
Mediators and Ukrainian representatives accused the separatists of scuppering an agreement despite growing international pressure to defuse a bloody upsurge in fighting that has left scores dead in recent days.
The Organization for Security and Co-operation in Europe (OSCE), which is involved in the talks along with Russia, said that rebel negotiators in Minsk "were not even prepared to discuss implementation of a ceasefire and withdrawal of heavy weapons."
Instead the insurgent representatives called for a total revision of an earlier Kremlin-backed peace plan signed in September that has formed the basis for all negotiations, the OSCE said in a statement.
The rebels say they now want to redraw the demarcation line between the two sides to include gains they have made since ripping up a shaky truce and pushing into Ukrainian territory.
Kiev has rebuffed this demand and said the rebels' position has thrown any future peace talks into doubt.
"Unfortunately the peace process is now under threat," Valeriy Chaly, the deputy head of Ukraine's presidential administration wrote on his Facebook page.
- 'Constant battles' -
The fiercest fighting on the ground is focused around the strategic town of Debaltseve, a railway hub between rebel bastions Donetsk and Lugansk, where rebels are trying to encircle government forces.
Ukraine military spokesman Volodymyr Polyovyi said that "constant battles" were ongoing around the town but denied insurgent claims that they have trapped some 8,000 government troops.
Civilians who have fled describe increasingly dire conditions in the town -- which once had a population of some 25,000 -- with water and electricity cut and the remaining inhabitants living in underground shelters.  
Western governments and Ukraine have accused Russia of sending regular troops and arms to bolster the rebels and spearhead the latest offensive -- claims Moscow has repeatedly denied.
The rebels, however, are equipped with the heavy weaponry of a regular army, hardware they claim to have captured from fleeing Ukrainian forces.
Russian President Vladimir Putin, French President Francois Hollande and German Chancellor Angela Merkel talked to each other by phone ahead of the peace meeting on Saturday, urging the warring factions to agree a truce in fighting that has left at least 5,100 people dead.
Moscow -- suffering the economic impact of harsh Western sanctions over the Ukraine crisis -- reacted cautiously to the collapse of the talks, saying that they "needed time to evaluate them."
The 28-nation EU on Thursday extended through September a first wave of targeted sanctions it had slapped on Moscow and Crimean leaders in the wake of Russia's March seizure of the Black Sea peninsula from Ukraine.
US Secretary of State John Kerry is set to jet into Kiev on Thursday to pledge Washington's support for the war-torn nation during talks with President Petro Poroshenko and Prime Minister Arseniy Yatsenyuk.
Source: AFP