Pro-Russian separatists vowed Monday to mobilise up to 100,000 fighters for their latest east Ukraine offensive as the United States mulled sending weapons to Kiev's outgunned forces after the latest truce bid collapsed.
Pro-Russian fighters patrol in streets of Makiivka, in the suburbs of the eastern Ukrainian city of Donetsk which is controlled by pro-Russian rebels, on February 1, 2015
The pledge to dramatically escalate a nine-month conflict that has already left at least 5,100 people dead came as the rebels battled to encircle the beleaguered transport hub of Debaltseve.
"There will be general mobilisation in the (separatist) Donetsk People's Republic in 10 days' time, we plan on mobilising up to 100,000 men," rebel leader Alexander Zakharchenko told the separatist news agency DAN.
Ukrainian army spokesman Andriy Lysenko said the rebel call-up meant they "don't have the human resources and haven't achieved their objectives, that is taking the strategic town" of Debaltseve.
Kiev authorities announced at the end of January that they also were calling up 50,000 troops in the face of the latest rebel offensive.
Fighting in Ukraine's eastern industrial heartland has intensified in recent days, with five Ukrainian soldiers and seven civilians killed in the last 24 hours.
The conflict claimed around 50 lives over the weekend, as the latest attempt at truce talks collapsed in acrimony in Minsk on Saturday.
- Call-up scepticism -
Kiev military spokesman Lysenko said Debaltseve town centre had been shelled and that government reinforcements had launched a counter-attack to stop rebels encircling the town.
Over the past three days Ukrainian forces had evacuated 1,872 people from three towns worst hit by fighting, including Debaltseve.
In the self-proclaimed rebel capital Donetsk, military aged males met the separatist leader's call-up announcement with scepticism.
"I wouldn't give it too much credence," said Alexander, 28.
"Either it's wrong or they're saying it for Ukrainian media," said the pro-separatist transport manager.
"But if it's true, the aim is to kill the entire population of Donetsk," he said, adding that Zakharchenko was "losing the support of those who supported him".
Web-designer Vitaly, 24, said the call-up would lead nowhere.
"Every day, I feel a little bit more a hostage" of the separatist authorities, he said.
- Lethal assistance -
The surge in fighting comes as Washington and NATO's military commander appear to be moving towards supplying arms to Ukrainian forces, The New York Times reported Sunday.
President Barack Obama's administration was reviewing whether to provide "lethal assistance", in addition to non-lethal aid such as body armour and medical equipment which it already supplies to Kiev, it said.
"A comprehensive approach is warranted, and we agree that defensive equipment and weapons should be part of that discussion," a Pentagon official told the Times.
US Secretary of State John Kerry is set to jet into Kiev on Thursday to pledge Washington's support during talks with President Petro Poroshenko and Prime Minister Arseniy Yatsenyuk.
Western governments and Ukraine have accused Russia of sending regular troops and arms to bolster the rebels and spearhead the latest offensive -- claims Moscow has repeatedly denied.
The rebels, however, are equipped with the heavy weaponry of a regular army, hardware they claim to have captured from fleeing Ukrainian forces.
- 'Not prepared for truce' -
The latest attempt at a negotiated ceasefire collapsed on Saturday, with the Organization for Security and Cooperation in Europe (OSCE), which is involved in the talks along with Russia, saying rebels "were not even prepared to discuss implementation of a ceasefire and withdrawal of heavy weapons".
The rebels say they now want to redraw the demarcation line between the two sides to include gains they have made since ripping up a shaky truce and pushing into Ukrainian territory.
The 28-nation European Union last week extended through September a first wave of targeted sanctions it had slapped on Moscow and Crimean leaders in the wake of Russia's March seizure of the Black Sea peninsula from Ukraine.
But deep divisions within the EU meant that there was no agreement on expanding broad sanctions targeting Russia's economy.