Ukraine's military said on December 22 that one of its soldiers was killed and two wounded in the previous 24 hours in the eastern part of the country.
A Defense Ministry statement said that Russia-backed separatists violated a frequently breached cease-fire 16 times using snipers, machine guns, and mortars.
Separatists, meanwhile, claimed that government forces violated the cease-fire 28 times using assault rifles, grenade launchers, mortars, and artillery.
Fighting between Kyiv's forces and the Russia-backed separatists who hold parts of the Donetsk and Luhansk regions has killed more than 10,300 people since April 2014.
Cease-fire deals announced as part of the Minsk accords -- September 2014 and February 2015 pacts aimed to resolve the conflict -- have failed to hold.
Rights groups and Western officials have voiced alarm about a recent increase in hostilities.
A new cease-fire agreed ahead of the holiday season was set to begin at midnight between December 22 and 23.
The planned cease-fire, as well as a planned prisoner exchange, were discussed by Russian President Vladimir Putin and German Chancellor Angela Merkel during a phone call on December 21, the Kremlin said.
Putin also explained to Merkel why Russia withdrew its military observers from a joint group monitoring the truce in eastern Ukraine, according to the Kremlin.
Putin said the Russian move announced earlier this week was due to what the Kremlin said were “restrictions and provocations” by Ukrainian authorities.
Kyiv has criticized Moscow’s decision, saying it could fuel hostilities.
With reporting by Interfax, TASS, and AP