Ukraine's rebels disavowed a new truce in a key town on Sunday, hours after it took effect, in a blow to a fragile peace plan aimed at ending 10 months of conflict.
Guns fell abruptly silent at midnight across much of eastern Ukraine in line with the ceasefire agreement, reached after a week of marathon diplomacy led by France and Germany.
But pro-Russian rebels announced they would not observe the truce at Debaltseve, saying it did not apply to the town where most fighting has taken place in recent weeks and where Ukraine army forces have since been encircled.
"Of course we can open fire (on Debaltseve). It is our territory," Eduard Basurin, a senior rebel commander, told Reuters.
"The territory is internal: ours. And internal is internal. But along the line of confrontation there is no shooting."
Elsewhere, pro-Kiev officials told AFP that two civilians were killed when shelling hit the town of Popasna in Lugansk region just 20 minutes after the start of the ceasefire at midnight.
Ukraine's military said that across the conflict zone its forces had come under fire 10 times but that shooting had tailed off since 3:00am.
"In general the situation in east Ukraine appears to be heading towards stabilisation," military spokesman Andriy Lysenko told AFP.
It was unclear what impact the rebels' disavowal would have across the battle zone, where the emphasis was mostly on ensuring the truce would stick. Both sides said their forces had stopped shooting and blamed what firing there was on the enemy.
Kremlin spokesman Dmitry Peskov said the truce must be implemented "unconditionally" as agreed on Thursday, but made no mention of whether Moscow believes the ceasefire applies to Debaltseve. He declined to comment on Basurin's remarks.
Reuters journalists in nearby towns heard volleys of artillery from the direction of Debaltseve in the morning after a night that had been mostly quiet.
Ukrainian forces have for weeks been holding out in the town, which sits astride a railway junction in a pocket between the two main rebel strongholds.
Washington says Russia's regular military, armed with tanks and missile launchers, carried out an operation in the days before the truce to encircle Debaltseve.
Reuters journalists operating on the rebel side have seen armoured columns of troops without insignia arriving in the area in recent days.
Ukraine's President Petro Poroshenko, wearing the uniform of the armed forces supreme commander, said in a midnight televised address in the capital Kiev that he had ordered troops to stop firing in line with the truce. He said there was still alarm over the situation around Debaltseve.
The Ukrainian military said on Sunday morning that the ceasefire was being "generally observed". Its forces had been shelled 10 times since the truce took effect in "localised" incidents. Nine of its soldiers were killed on Saturday but nonesince the truce took effect, a spokesman said on Sunday morning.
The ceasefire, negotiated in four-power talks in Minsk on Thursday, foresees creation of a neutral “buffer zone” and withdrawal of heavy weapons responsible for many of the 5,000 deaths in a conflict that has caused the worst crisis in Russia-West relations since the Cold War a generation ago.
But trust is low on all sides and scepticism remains high after the collapse of a previous ceasefire, also agreed in the Belarussian capital.
FRANCE 24’s Gulliver Cragg reports from Ukraine’s capital Kiev
Kiev and NATO have long charged that Moscow has supplied pro-Russian separatists in eastern Ukraine with arms and men, and Washington and its allies have slapped Russia with a series of economic sanctions. Russian President Vladimir Putin denies Moscow is involved in fighting for territory Putin calls “New Russia,” although Western officials cite overwhelming evidence to the contrary.
Poroshenko said that if Ukraine were slapped once, it would not offer the other cheek. But, seated alongside armed forces chief of staff Viktor Muzhenko, he added: "I very much hope that the last chance to begin the long and difficult peaceful process for a political settlement will not be wasted."
In the hours leading up to the ceasefire, heavy artillery and rocket fire roughly every five seconds had reverberated across Donetsk, the main regional city in the east which is under the control of the secessionists.
US Secretary of State John Kerry urged implementation of the ceasefire in a telephone call with his Russian counterpart Sergei Lavrov and expressed concern about efforts by Russia and the separatists to cut off Debaltseve.
US President Barack Obama expressed "deep concern" about the violence around Debaltseve prior to the ceasefire, in a telephone call with Poroshenko, the White House said. Obama also spoke to German chancellor Angela Merkel, who negotiated the ceasefire along with President Francois Hollande of France at all night talks with the leaders of Ukraine and Russia.
The Kremlin said the four leaders who negotiated the truce would continue to speak by phone.
Maxim, a rebel fighter at a checkpoint on a road from Donetsk to government-held Dnipropetrovsk, told Reuters it was indeed quiet but he did not expect the ceasefire to hold.
"Truce? I doubt it. Maybe 2-3 days and then they will start shooting again. This is all for show. The OSCE is driving around here, so of course they are being quiet," he said. The Organization for Security and Cooperation in Europe has monitors to observe the truce.
(FRANCE 24 with REUTERS, AFP)