Ukrainian government troops and Russia-backed rebels faced a deadline Tuesday to start pulling back heavy weapons from the front line in eastern Ukraine. Associated Press reporters saw no signs of it on the ground. (Feb. 17) AP 
 
 Separatist rebels help an injured comrade near a hospital in Donetsk, Ukraine, on Feb. 16, 2015. (Photo: Alexander Ermochenko, European Pressphoto Agency) 
 
 Pro-Russian separatists claimed to take control of most of the strategic Ukrainian city of Debaltseve on Tuesday, as a deadline passed for the combatants to pull back their heavy weapons according to a cease-fire agreement. 
 
 The Donetsk News Agency, a separatist mouthpiece, quoted the rebels' so-called defense ministry as saying Tuesday that their forces had pushed government troops out of Debaltseve and are now controlling a large part of the city. 
 
 Separatist defense minister Vladimir Kononov said 80% of the city was under his forces' control, according to Russian news site Life News. Separatist leader Alexander Zakharchenko received medical treatment after he was shot in the ankle during street fighting in the city, Life News reported. 
 
 While fighting continues at the strategic railway hub, Ukrainian military spokesman Andruy Lysenko said government forces continue to hold their position in part of the city. Ukraine's military also said some of its soldiers in Debaltseve were captured in an ambush. 
 
 Valery Chaly, chief of the Ukrainian presidential administration, said Kiev wants the European Union and NATO to "resolutely condemn" the separatists for violating the deals, the Associated Press reported, citing Russian news agencies. 
 
 Ukrainian military spokesman Anatoliy Stelmakh said in televised comments early Tuesday that the separatists continued to attack their positions overnight, and that the pullout hinges on the cease-fire being fully observed. 
 
 "As soon as the militants cease fire, the Ukrainian side will begin to withdraw heavy weaponry from the frontline," he said. 
 
 Ukrainian government troops and Russia-backed separatists have failed to start pulling back heavy weaponry from the front line in eastern Ukraine as the deadline to do so passed. 
 
 Under a cease-fire agreement deal brokered Thursday in Minsk, Belarus, among the leaders of Ukraine, Russia, France and Germany, the warring sides were to begin withdrawing heavy weapons from the front line Tuesday. 
 
 Russian news agency RIA Novosti quoted rebel leader Andrei Purgin as saying that the separatists plan to discuss the possible withdrawal of the weaponry later Tuesday with representatives of Ukraine, Russia and the Organization for Security and Cooperation in Europe, which is charged with monitoring the cease-fire. 
 
 A cease-fire between government troops and pro-Russian separatists came into effect Sunday, but fighting over Debaltseve has continued. 
 
 U.S. and other Western leaders expressed concern on their Twitter accounts over the ongoing at Debaltseve, which they blamed on the separatists. 
 
 "Concerned by the situation in #Ukraine as separatists refuse to observe cease-fire in Debaltseve & deny #OSCE access," tweeted NATO commander Philip Breedlove. 
 
 Geoffrey Pyatt, the U.S. ambassador to Kiev, tweeted: "Very clear that non-compliance around #Debaltseve lies with separatists + Russian military units." 
 
 On Tuesday, Kiev reported artillery strikes overnight around Debaltseve, while the situation in the rest of the war zone appeared to be calm. 
 
 On Monday, separatists launched 112 attacks in 24 hours, 88 of them on Debaltseve, according to Ukraine's UNIAN news agency, citing the Ukrainian military. 
 
 Up to 5,000 government troops are in the city, which has rail lines that connect the separatist regions of Donetsk and Luhansk with Russia. 
 
 Eastern Ukraine shows signs of shelling which would mean a violation the ceasefire between Ukrainian soldiers and pro-Russian separatists. Julie Noce reports. Video provided by Reuters Newslook 
 
 Zakharchenko, the rebel leader, said the cease-fire that began Sunday does not apply to Debaltseve because it is within the region already held by the rebels and was not mentioned in the agreement approved last week. 
 
 State Department spokeswoman Jen Psaki expressed "grave concern" over the fighting around Debaltseve. 
 
 "These aggressive actions and statements by the Russia-backed separatists threaten the most recent cease-fire and jeopardize the planned withdrawal of heavy weapons," as called for in the agreement reached last Thursday, Psaki said. 
 
 President Obama is weighing whether to give Ukraine more weapons to repel the separatists but has delayed a decision to see if the fighting ebbs. 
 
 The leaders of Ukraine, Russia and Germany discussed the cease-fire in a phone call late Monday. The office of German Chancellor Angela Merkel reported that they agreed on "concrete steps to enable an observation" of the situation in Debaltseve by the OSCE. 
 
 OSCE representatives, however, did not manage to get to Debaltseve on Monday because of heavy fighting there. 
 
 Merkel and Ukrainian President Poroshenko appealed to Russian President Vladimir Putin to use his influence on the separatists to ensure that they stop fighting. 
 
 Contributing: Associated Press 
 
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 Media playback is unsupported on your device Media caption The ceasefire is under "impossible strain", says Jonny Dymond 
 
 Fierce fighting is reported inside the key Ukrainian town of Debaltseve despite a ceasefire agreed last week. 
 
 Rebels say they have taken most of Debaltseve, a transport hub, but the government says it is still holding its positions. 
 
 International observers tasked with monitoring the ceasefire have been unable to enter the town. 
 
 Ukraine's president described rebel attempts to take the town as a "cynical attack" on the ceasefire. 
 
 "Today the world must stop the aggressor," Petro Poroshenko said in a statement posted on his website. 
 
 "I call on the permanent members of the UN Security Council to prevent further violation of fundamental principles and rules of the UN and the unleashing of a full-scale war in the very centre of Europe." 
 
 Speaking on a visit to Hungary, Russian President Vladimir Putin said he hoped the ceasefire agreements would be observed by both sides. 
 
 French Foreign Minister Laurent Fabius said "fundamental" parts of the ceasefire were not being respected, referring to the Debaltseve fighting and withdrawal of heavy weapons. 
 
 Earlier, both sides failed to begin the withdrawal, despite a Monday deadline agreed in the truce. 
 
 The two sides were given until two days after the latest ceasefire came into effect to start the pullout. 
 
 Analysis: Paul Adams, BBC News, Kramatorsk 
 
 The wealth of claim and counter-claim around Debaltseve speaks volumes. It's hard to confirm any of today's stories. 
 
 Controversy surrounds the fate of dozens of government troops - rebel sources say they surrendered, while the army contends they were captured after running out of ammunition during an ambush. 
 
 The rebels say Debaltseve is not covered by the ceasefire agreement reached last week in Minsk and continue to insist that it's an "internal" matter. Between April and July last year, the town was in rebel hands. It sits astride the railway line linking two rebel strongholds, Donetsk and Luhansk. 
 
 Ukrainian TV has shown pictures of text messages sent to government soldiers in Debaltseve, allegedly from Russia. "Poroshenko and his generals have betrayed you," the messages read, referring to the Ukrainian president. "There's no need for you to die for them." 
 
 Why is conflict so violent? 
 
 Who benefits from ceasefire deal? 
 
 Explaining the conflict in maps 
 
 Sources in the self-proclaimed Donetsk People's Republic (DPR) said Debaltseve police station and railway station had been taken, and at least 80% of the city was under rebel control. 
 
 According to later reports, the city's military HQ - where many government troops are based - has also been surrounded. 
 
 Image copyright Reuters Image caption Government artillery outside Debaltseve. Neither side has withdrawn its heavy weaponry as yet 
 
 Image copyright Reuters Image caption This car carrying journalists and a wounded driver fled shelling near Debaltseve on Tuesday 
 
 Image copyright AP Image caption Ukraine's military says it won't withdraw heavy weapons until it sees rebels do the same 
 
 DPR spokesman Eduard Basurin said government forces had stepped up their bombardment and were heading towards the rebel-held town of Lohvynove in an attempt to break through to Debaltseve. 
 
 He added that the rebels intended to withdraw heavy weapons from "quiet sectors" of the front line, but gave no time-frame. 
 
 The rebels said that up to 300 Ukrainian troops in Debaltseve had surrendered, and Russian TV showed footage of what it said were 72 captured soldiers. The Ukrainian government said a group had been taken prisoner after an ambush but denied large-scale surrenders. 
 
 The Ukrainian military said there was intense fighting in the streets and confirmed that the rebels were in control of parts of the city. 
 
 "Our troops are holding their positions, and they are well within their rights to return fire and hold the positions that they have held for several months," Interfax quoted spokesman Andriy Lysenko as saying. 
 
 'Safe corridor' 
 
 A National Guard source in the area told the BBC that government forces had regained control of the supply route, enabling them to get food and medicine into the town and wounded soldiers out. 
 
 Meanwhile, Russia's LifeNews website reported that rebel leader Alexander Zakharchenko had been lightly wounded in the leg during the fighting in Debaltseve and had been evacuated from the city. 
 
 Rebels have offered Ukrainian troops under siege there a safe corridor to leave. 
 
 Although Debaltseve has suffered weeks of artillery exchanges, correspondents say this is the first fierce fighting inside the town. 
 
 Most of Debaltseve's 25,000 population have been evacuated but about 7,000 civilians are still believed trapped by the fighting, according to Amnesty International. 
 
 The BBC's David Stern in Kiev says there is great concern about the humanitarian situation, with water now running out. 
 
 Minsk agreement: Key points 
 
 Ceasefire from 00:01 on 15 February (22:01 GMT 14 February) 
 
 Heavy weapons to be withdrawn, beginning on 16 February and completed in two weeks - beyond a buffer zone behind the current front line for Ukrainian forces and behind the September front line for separatist forces 
 
 All prisoners to be released; amnesty for those involved in fighting 
 
 Withdrawal of all foreign troops and weapons from Ukrainian territory. Disarmament of all illegal groups 
 
 Ukraine to allow resumption of normal life in rebel areas, by lifting restrictions 
 
 Constitutional reform to enable decentralisation for rebel regions by the end of 2015 
 
 Ukraine to control border with Russia if conditions met by the end of 2015 
 
 The ceasefire, which came into effect on Sunday, has been broadly observed but separatists insist the agreement does not apply in Debaltseve because they have the town almost surrounded. 
 
 Denis Pushilin, a spokesman for the Donetsk People's Republic, described Debaltseve as "internal territory" and said fighting for it was "a moral thing". 
 
 "We do not have the right [to stop fighting]," he told Reuters. 
 
 In the neighbouring Luhansk region, separatist leader Igor Plotnitsky said he had begun pulling back his tanks and artillery in line with the ceasefire agreement. His claim could not be independently verified. 
 
 Image copyright AP Image caption Ceasefire monitors have been unable to visit Debaltseve 
 
 Ukraine's pro-Western government says Russia is supporting the separatists with troops and weapons, but the Kremlin has consistently denied this. 
 
 Meanwhile, the leaders of Germany, Ukraine and Russia discussed the crisis in an overnight phone call. 
 
 Germany said they had agreed "concrete measures" for observers to have greater access, but gave no details. 
 
 Observers from the Organization for Security and Co-operation in Europe (OSCE), who are charged with monitoring the ceasefire, have been trying to reach Debaltseve after being denied access by pro-Russian rebels on Sunday. 
 
 The withdrawal was due to start no later than the second day after the truce came into effect and be completed within two weeks, creating buffer zones 50-140km (30-85 miles) wide. 
 
 Officials say more than 5,400 people have been killed since the conflict erupted in eastern Ukraine in April, but the UN believes the actual death toll to be much higher.
– A ceasefire in Ukraine was supposed to begin early Sunday, but the town of Debaltseve is seeing its worst clashes yet. Both rebels and the government are claiming to have control of the town, the BBC reports. Outside Debaltseve, relative peace has held—but rebels see the town as an exception to the ceasefire, with one telling the BBC it's "internal territory." Observers have been unable to access the town even as the Ukrainian military reports five deaths in 24 hours. Neither side appears to be following a deadline to pull heavy weapons from the area; each side says it's waiting for the other to get started on the withdrawal. Rebels are due to meet with international officials later today to discuss the matter, USA Today reports. Some 5,000 Ukraine troops are in the city, which USA Today describes as an important rail hub. The US is condemning the separatists' latest moves: "These aggressive actions and statements by the Russia-backed separatists threaten the most recent ceasefire and jeopardize the planned withdrawal of heavy weapons," says a state department official. President Obama could send more weapons to government forces, pending further developments.