World Bulletin / News Desk
The truce envisages the creation of a neutral "buffer zone" and withdrawal of heavy weapons responsible for many of the 5,000 casualties in a conflict that began almost a year ago and gave rise to the worst crisis in relations betweenRussia and the West since the Cold War a generation ago.
"Ahead of midnight, rebels are trying to complete tactically important plans to enlarge the territory under their control, primarily in the direction of Debaltseve," spokesman Andriy Lysenko said at a daily televised briefing in Kiev.
Debaltseve, a strategic transport hub northeast of the rebel-controlled stronghold city of Donetsk, has been the focus of some of the fiercest fighting in recent weeks.
Heavy shelling could be heard at a rebel checkpoint 10 km (six miles) from the Debaltseve, a Reuters witness said, reporting outgoing artillery rounds almost every minute.
A column of new military vehicles and artillery passed through the checkpoint in the direction of Debaltseve. The checkpoint was manned by several dozen, professional-looking combatants. Tanks and armoured vehicles could also be seen.
Speaking on condition of anonymity, a rebel at the checkpoint said local fighters were being supported by "guests from Russia."
Spokesman Lysenko said separatist forces continued to be reinforced by fighters and military equipment crossingUkraine's eastern border from Russia over the past 24 hours. Moscow denies bolstering the separatists with armour and troops although Western officials cite overwhelming evidence to the contrary.
REGIONAL AUTONOMY PART OF DEAL
The rebels have advanced far past the line of an earlier ceasefire deal, agreed in September, and the new accord appears to envisage them withdrawing their guns around 75 km, to take them back behind it, while Ukrainian guns would move 25 km back.
Thursday's four-power accord also prescribed constitutional reform to give eastern Ukraine, where many Russian speakers live, more autonomy. Kiev has made clear it rejects independence for the "People's Republics" the rebels have declared.
Tatyana Demchenko, deputy commander of the rebel unit in the town of Horlivka, said she had little faith the ceasefire would hold. "They'll shoot at us and we have to remain silent? Militias may receive the order not to open fire, but what - we sit and die in shelling? If they don't shoot, we won't," she said, holding two grenades in her hands.
Ukrainian President Petro Poroshenko said the country had reached an important crossroads between war and peace.
"Either the enemy stops shooting and embarks on de-escalation ...or the enemy escalates the conflict for us and forEurope and the whole world," he said at a ceremony for border guards shown on television.
Seven Ukrainian service personnel have been killed and 23 wounded in fighting in the past 24 hours, Lysenko said.
The Group of Seven industrialised countries issued a statement late on Friday calling on all sides to refrain from actions that would hinder the start of the ceasefire. It said G7 countries were ready to take "appropriate measures" against those who violate the agreement, an apparent threat of more punitive economic sanctions against Russiashortly.
Ukraine's pro-Western president said he was not naive and wanted to make clear the country was a long way from peace.
"Nobody has a strong belief that the peace conditions which were signed in Minsk will be implemented strictly," Petro Poroshenko said.
Away from the battlefield, disagreements surfaced over whether a rebel amnesty or the release of a Ukrainian pilot detained by Russia were part of the ceasefire deal.
Western diplomats said the European Union would go ahead on Monday with planned sanctions against 19 Ukrainian separatists and Russians, despite the ceasefire.
NATO and the United States said the fighting ran counter to the spirit, if not the letter of the agreement and U.S. officials said further sanctions were still on the table.
The French, German, Russian and Ukrainian leaders are expected to speak again by phone on Saturday in the hours before the ceasefire is due to take effect.
Kremlin spokesman Dmitry Peskov said Moscow expected all points of the deal to be implemented, but that Russiahad not promised to free Nadezhda Savchenko, a detained Ukrainian pilot that Kiev wants free. Her case would be decided by a Russian court, he said.
Ukraine said it had not agreed to an amnesty for all rebels, drawing an angry response from the separatists.
Russia's economy minister said he hoped sanctions would be lifted soon.
VAST "BUFFER ZONE"
The deal calls for the withdrawal of heavy weapons from the front line when and if the ceasefire has taken hold, and constitutional reform to give eastern Ukraine more autonomy.
The rebels have advanced far past an earlier ceasefire deal, agreed in September, and the new agreement appears to envisage them pulling their guns back around 75 km, to take them back behind it, while Ukrainian guns would move 25 km back.
This would leave a buffer zone 50 km wide, a challenge for the monitors from the Organization for Security and Cooperation in Europe who are expected to patrol it. It also appears to take more territory outside Kiev's control.
The White House, under pressure from Congress to provide arms to the stretched Ukrainian military, said the deal was "potentially significant" but urged Russia to withdraw soldiers and equipment, and give Ukraine back control over its border.