Ukraine's military yesterday reported losing 23 servicemen in clashes across the separatist east that threatened to shatter slim Western hopes of a truce in Europe's deadliest conflict in decades.
The defence ministry said the toll included 19 troops who died in a hail of rockets fired from a truck-mounted Grad rocket launcher system - a type of weapon both Kiev and Washington insist could only have been covertly supplied to the rebels by Russia.
The official spokesman of Ukraine's intensifying eastern assault added that 93 servicemen had sustained "wounds and contusions of varying severity".
"The rebels will pay for the life of every one of our servicemen with tens and hundred of their own," Ukraine's Western-backed President Petro Poroshenko told an emergency security meeting.
Yesterday's official death toll is the highest since Poroshenko tore up a brief ceasefire with the rebels on July 1 and relaunched an offensive that managed to dislodge the militias from key eastern strongholds they had held since early April.
The military separately claimed "eliminating" nearly 100 fighters in one of Ukraine's bloodiest days since the start of the crisis last November as anti-government protests spiralled into revolution and a protracted standoff with pro-Russian rebels.
The tide in the eastern uprising turned last weekend when resurgent government forces flushed out the separatists from a string of eastern towns and cities that hold historic Russian ties.
Most of the militias have since retreated to Donetsk and the neighbouring industrial city of Lugansk - both capitals of their own "People's Republic" that are seeking annexation by Russia.
The conflict has claimed the lives of more than 500 people and displaced tens of thousands across a rustbelt that had long been the economic engine of the troubled post-Soviet state.
Amnesty International said yesterday it had recorded "hundreds" of abductions and acts of torture committed by the separatists during the uprising.
But it also noted that "excessive force may have been used ... by Ukrainian forces" on several occasions - a charge repeatedly made by Moscow.
The conflict has further splintered Ukraine's culturally fractured society and left some ethnic Russians feeling marginalised by the more nationalistic leaders who have taken power. Many have escaped across the eastern border in search of a new home.
"Everything is shutting down," said a man in his 50s as he listened to the echoes of gunfire rolling in from a fierce clashes being waged yesterday outside Donetsk International Airport, a gleaming hub shuttered since facing a bloody rebel attack at the end of May.
"There is nothing to do here. No work - and it is getting too dangerous," he said.
Poroshenko now finds himself trapped between European pressure to agree an immediate truce and massive domestic support for his troops to finish off an insurgency that has threatened the 45-million-strong nation with disintegration and economic collapse.
Germany and France have been spearheading EU efforts to secure a truce and win promises from the Kremlin to stop meddling in Ukraine. They hope to avoid further European sanctions on Russia that might damage their energy and financial ties with Moscow.
But they have found Poroshenko - boosted by recent successes on the battlefield and bound by promises made at the May election - looking increasingly unwilling to call off the offensive.