Ukraine has lost eight soldiers in a dramatic spike in fighting with pro-Russian gunmen that further imperilled a truce Washington's top European envoy is desperately trying to salvage in Kiev.
Separatist rebels also reported the death of two fighters and a civilian in shelling across the eastern industrial heartland of the former Soviet nation that took a decisive tilt toward the West more than a year ago.
Kiev's Security Council said early on Wednesday that the previous 24 hours had witnessed "some of the most intense bombardments of Ukrainian territory since the signing of the Minsk (truce) agreement" in February.
It said 16 servicemen had also been wounded without specifying where the deadly exchanges of heavy weapons fire had broken out.
"The latest events are proof of yet another attempt by Russia and its puppet to wreck the Minsk agreement and restart active military hostilities," the Ukrainian Security Council said.
The insurgents said on their main website that the number of Ukrainian attacks had more than doubled to 85 from the 35 recorded Tuesday.
The United Nations believes that more than 6500 people have died and nearly 1.5 million been left homeless by unceasing violence that Ukrainian President Petro Poroshenko had vowed to resolve within days of being elected in May 2014.