Kiev: Ukraine on Friday said that dozens of tanks and truckloads of soldiers had crossed from Russia into Kremlin-backed rebel territory, as five servicemen were killed in the latest fighting to tear apart a nominal ceasefire.
The allegations that Moscow is stepping up reinforcements for the insurgents stoked fears that both sides could slide into a return to all-out fighting.
A column of 32 tanks, 16 howitzer cannons and 30 trucks carrying troops and equipment crossed the border into the separatist-held Lugansk region yesterday, Ukrainian military spokesman Andriy Lysenko said, adding that another convoy including three mobile radar stations had also entered the same area.
NATO said it had not verified the claims of the latest incursion but stated it had observed "a recent increase in Russian troops and equipment along the eastern border of Ukraine".
"If this crossing into Ukraine is confirmed it would be further evidence of Russia's aggression and direct involvement in destabilising Ukraine," a NATO military officer said.
However, the Russian defence ministry said Friday that a string of Western accusations concerning troop movements around the Ukraine border were "untrue".
Lysenko said five Ukrainian soldiers were killed and 16 injured in the past 24 hours in clashes between government forces and pro-Moscow rebels, underscoring the emptiness of a two-month truce that both sides continue to insist they are respecting.
Fifteen civilians were wounded by shrapnel in the separatist bastion of Donetsk, the mayor's office said, in a night of shelling in two neighbourhoods near the ruins of the airport, where government troops are holding out.
An AFP journalist reported heavy artillery bombardments had resumed in the area around the strategic transport hub late Friday.