Within hours of the start of the scheduled ceasefire in eastern Ukraine, the warring sides have been trading accusations of new attacks. President Poroshenko called the truce a "last chance" for a political settlement.
In a live broadcast Ukrainian President Petro Poroshenko issued a ceasefire order for all the country's armed forces to hold their fire from one minute after midnight Kyiv time (2201 UTC). "I very much hope that the last chance to begin the long and difficult peaceful process for a political settlement will not be wasted," he said.
Military spokesman Vladyslav Selezynov said the Ukrainian armed forces immediately fulfilled the order.
Shelling suddenly stopped at midnight in the eastern Ukrainian city of Donetsk after Poroshenko's order but accusations of violations were quick to follow.
The US State Department said images from eastern Ukraine offered "credible pieces of evidence" that the Russian military had deployed artillery and multiple rocket launchers around the strategic railway town of Debaltseve, in order to fire at Ukrainian forces.
"We are confident that these are Russian military, not separatist systems," State Department spokeswoman Jen Psaki said in a statement Saturday.
Ukrainian security services chief Valentyn Nalyvaichenko said that 50 minutes after the deadline, there was artillery fire from an area under the control of a Cossack unit manned by Russian citizens.
Rebels accused the Ukrainians of deploying artillery shortly after midnight. Debaltseve is a strategic rail junction that lies between the two main rebel-held regions. It has been the focus of recent fighting.
"In the interests of preventing deaths of the civilian population, precise fire is being deployed toward the enemy's positions," Basurin said, according to the Donetsk News Agency, a rebel media source.
Speaking to his Russian counterpart Sergey Lavrov by telephone Saturday, US Secretary of State John Kerry had expressed concern about what he called efforts by Russia and the separatists to cut off Debaltseve in advance of the cease-fire.
Human rights group Amnesty International said it remains deeply concerned for civilians trapped by the fighting in and around Debaltseve.
Cessation of hostilities is only the first point in a series of planned steps agreed to in Belarus last week in talks promoted by Germany and France. Withdrawal of heavy weaponry from the front line, creating a zone roughly 50-140 kilometers (30-85 miles) wide is to begin Monday and be completed in two weeks. There are no provisions for the withdrawal of troops.
The peace plan also requires the Ukrainian government to resume paying pensions and state benefits to citizens in rebel-held territory.
jm/sb (AFP, Reuters, AP)