Ukraine said pro-Russian separatists could be moving in from beyond the front line after an explosion killed two people at a memorial rally in an eastern city.
Four people were arrested after the blast which killed a policeman and a demonstrator at the rally in Kharkiv, the biggest city in the east, 200 km. from the war zone.
Officials in Kiev said the suspects had been armed and trained by Russia, Reuters reported Monday.
The incident happened a week after a ceasefire agreement that Moscow-backed rebels ignored to capture a strategic town.
Kiev and its western allies are trying to determine whether the separatists will now halt, or advance deeper into territory the Kremlin calls “New Russia”.
Germany and France mediated the peace deal that came into effect a week ago and said they still hope it can be resurrected, even though the rebels ignored it to inflict one of the worst defeats of the war, seizing the town of Debaltseve after encircling thousands of Ukrainian troops.
In signs that there may be at least a pause now that the rebels achieved that objective, government and separatist forces exchanged prisoners overnight.
The rebels said on Sunday they would begin withdrawing artillery from the front.
But Kiev said Moscow was moving more troops and armor into eastern Ukraine near a port it fears is the next target. Russia denies it has troops in eastern Ukraine.
Ukrainians held marches and memorial services on Sunday for 100 people killed a year ago during an uprising that toppled a pro-Russian president and led to the war in which more than 5,500 people have since been killed.
At the rally in Kharkiv, amateur footage posted on the internet showed a few hundred marchers with Ukrainian flags, who shouted “glory to the heroes!” just before being hit by an explosion.
Demonstrators and bystanders, including a woman pushing a baby in a pram, fled in panic. A wounded man in military uniform lay in the snow shouting for help.
“Today is memorial Sunday, but on this day terrorist scum revealed its predatory nature,” President Petro Poroshenko said on Facebook. “This is a brazen attempt to expand the territory of terrorism.”
– Contact us at [email protected]