A massive assault by Russian-backed insurgents on a Ukrainian force hanging on to a ruined airport near the rebels` main stronghold prompted Germany on Tuesday to announce urgent new peace talks.
Blasts of incoming and outgoing artillery echoed all night across Donetsk -- a once bustling industrial hub but now the crucible of one of Europe`s worst humanitarian and diplomatic crises since the Cold War.
Rebel city administration member Ivan Prikhodko said two civilians were killed and eight seriously wounded when a shell hit a bus stop on the war-wrecked northwestern edge of town.
"The bus stop itself and a store nearby have been levelled," Prikhodko told AFP by telephone.
The past week`s escalation in fighting and effective shredding of a repeatedly-violated September truce have been accompanied by claims from Kiev`s pro-Western leaders that 700 new Russian soldiers have deployed across the border into Ukraine`s separatist east.
Russia`s defence ministry called the charges "absolute nonsense" and once again denied supporting the rebel cause.
The Kremlin accused Ukrainian President Petro Poroshenko of rejecting a troop withdrawal proposal submitted last week by Russia`s Vladimir Putin.
Ukraine meanwhile set in motion a previously-approved fourth wave of military call-ups since the start of hostilities in mid-April.
The 50,000 new volunteers and reservists will be mostly deployed in the war zone in stages stretching over three months. The infusion of additional forces reflects Ukraine`s increasingly frantic attempt to defend itself against what it views as Russian "aggression".
The blame game between Moscow and Kiev is being watched by European leaders who hope to see a quick end to a nine-month conflict that has plunged East-West relations into crisis and sparked a damaging sanctions war.
The Kremlin said the resumption of what Kiev now says is full-scale war means no peace summit between the neighbours` presidents and the leaders of Germany and France was likely any time soon.
But Germany said that the four countries` foreign ministers would still meet in Berlin on Wednesday to see if they could somehow find a compromise that could stem the violence.
"The chief aim now is to prevent a further deterioration of the military conflict and a renewed political escalation between Kiev and Moscow," German Foreign Minister Frank-Walter Steinmeier said in a statement. "This is worth every effort."The most bitter fighting focused on the international airport that Ukraine spent nearly a billion dollars rebuilding for the Euro 2012 football championship matches staged in Donetsk.
The rebel militias -- armed with heavy artillery guns and Grad systems that fire up to 40 rockets in less than a minute -- have pulverised the once gleaming structure.
They reported capturing the airport on Monday after a weekend assault. Ukraine`s army said it was back in control by early Tuesday and was checking reports that a whole floor of the building had collapsed on defenders on Monday afternoon.
"The Ukrainian military cleared the area around the airport and destroyed the rebels` fighting positions," military spokesman Vladyslav Seleznyov told AFP on Tuesday.
The self-proclaimed Donetsk People`s Republic`s "defence minister" in turn accused Kiev`s units of "shelling residential districts" across the mostly Russian-speaking war zone.
"And it is the civilians who are really suffering -- not the militia troops," Eduard Basurin told the pro-Russian Donetsk News Agency.
Kiev says the rebels endanger civilians by stationing their artillery in residential districts and forcing Ukrainian forces to respond.
Western leaders have struggled to understand why fighting has erupted after a month-long lull that saw Poroshenko offer talks with Putin aimed at ending bloodshed that has claimed more than 4,800 lives.
But the flare-up coincided with the warring sides` attempt to establish a demarcation line between their armies that would define the confines of rebel-controlled lands.
Moscow insists that the separatists have the right to Donetsk airport under a prior agreement. Kiev denies ever accepting such terms.
Two top Western diplomats in Kiev said on Wednesday they believed that the rebels had made significant progress on the ground in recent days.
One of them added on condition of anonymity that the rebels appear to be trying to undermine European peace efforts in order to win more ground before a final partition agreement is reached.