A ceasefire agreed between Ukrainian forces and pro-Russian rebels has come into force. Leaders of France, Germany, Russia and Ukraine are expected to speak again to assess the truce's progress.
Ahead of the ceasefire deadline, fighting continued in eastern Ukraine with separatists pressing government forces in the town of Debaltseve and shelling killing at least one person in the rebel-held city of Donetsk.
Regional police chief Vyacheslav Abroskin said on Saturday there had been artillery bombardment on the strategic railway hub of Debaltseve, where Ukrainian forces were trying to hold on to their positions: "The rebels are destroying the town of Debaltseve. There are non-stop artillery bombardments of residential areas and buildings. The town is in flames," Abroskin wrote on Facebook.
The ceasefire which took effect at midnight in Ukraine (2200 UTC) was forged by the leaders of Ukraine, Russia, France and Germany following 16 hours of negotiation in the city of Minsk last Thursday. According to the Reuters news agency, shelling suddenly ceased in the city of Donetsk at midnight.
Earlier on Saturday, Russian President Vladimir Putin repeated his commitment to the ceasefire in a telephone call with German Chancellor Angela Merkel and French President Francois Hollande.
According to the French president's office, they all confirmed "the need for the ceasefire scheduled for midnight to be effective."
"Putin said the rebels were ready for the ceasefire," the statement added. Merkel, Hollande and Putin are expected to speak again by telephone with Ukraine's President Petro Poroshenko on Sunday, to assess the state of the ceasefire.
Respecting the truce
The pro-Moscow rebel chief in Donetsk, Alexander Zakharchenko earlier ordered his fighters to respect the truce, but to fend off any attacks "with all force and means." He also said any attempt by Ukrainian troops encircled in Debaltseve to escape the town after midnight, would be viewed as an act of aggression and violation of the truce.
Zakharchenko said: "there is not a word about Debaltseve in the Minsk accords."
Speaking during a visit to Peru, German foreign Minister Frank-Walter Steinmeier said on Saturday he had not expected such an intense surge in violence following Thursday's accord in Minsk. He urged all parties to conform with the ceasefire terms: "If it is going to be respected, we're going to witness it tonight," he said. "If we fail with these efforts now, everyone in the region ... will pay a high price."
Steinmeier said breaking the truce would threaten European security as well as "the possibility of cooperation in international institutions including the Security Council."
US President Barack Obama spoke with Merkel on Saturday, thanking her for her work in brokering the latest ceasefire. He also spoke with Poroshenko, according to the White House, "to express his sympathy for the mounting toll of the conflict in eastern Ukraine and his deep concern about the ongoing violence, particularly in and around Debaltseve."
The United Nations Security Council is expected to meet on Sunday for an emergency session.
In ten months of conflict, more than 5,300 people have been killed in eastern Ukraine.
jm/sb (Reuters, AP, AFP, dpa)