Russian on Friday accused Ukraine of attempting to disrupt a Russian humanitarian aid mission to eastern Ukraine and called for a ceasefire in the region to allow for the deliveries.
"We draw attention to the sharp intensification of military action by Ukrainian forces with the apparent aim to stop the path, agreed on with Kiev, of a humanitarian convoy across the Russia-Ukraine border," the Foreign Ministry said in a statement.
Ukraine's President Petro Poroshenko earlier said artillery destroyed a "significant" part of a Russian armored column that crossed into Ukraine during the night.
Separately, a Ukrainian military spokesman said Ukrainian forces had tracked the Russian armored column as soon as it crossed onto Ukrainian soil.
"Appropriate actions were undertaken and a part of it no longer exists," military spokesman Andriy Lysenko told journalists.
Meanwhile, Finnish President Sauli Niinisto said on Friday he hoped a Russian humanitarian aid delivery to eastern Ukraine would pave the way for a ceasefire between the government and pro-Russian rebels there.
Speaking after talks with Russian President Vladimir Putin in Russia at his Black Sea residence in Sochi, Niinisto said an agreement had been reached between Ukraine, Russia and the International Committee of the Red Cross to let a Russian aid convoy of some 280 trucks enter eastern Ukraine.
"We hope that this news is a testimony to the potential strengthening of mutual trust and we very much need this mutual trust to take the next step ... that is for a ceasefire," he said.
However, it was unclear whether Niinisto, speaking through a translator, was simply referring to an agreement between Russia and Ukraine that the cargo could enter once it had been inspected, cleared and handed over to Red Cross supervision.
The convoy has idled for days near the Russia-Ukraine border, undergoing inspections and awaiting the final go-ahead from Kiev, which fears it may be a cover for a covert Russian military operation to help the rebels.
The ICRC in Geneva said it was not aware that a final agreement had been reached. Shortly before Niinisto spoke, the ICRC's representative in Kiev urged Russia and Ukraine to agree quickly on getting supplies from the aid convoy across the border to civilians, and said the ICRC would itself deliver them to people and health centers in the region.
But he said the ICRC was still waiting for "assurances from all parties to the conflict that our staff will be allowed to perform their tasks safely and with due respect for our humanitarian principles".
Niinisto cautioned that, for a ceasefire to be achieved, arms should not reach the rebels across the Russia-Ukraine border.
Kiev and its Western allies accuse Moscow of supporting and arming the rebels with supplies sent across the border, something that Moscow denies.
NATO Secretary General Anders Fogh Rasmussen said on Friday that a "Russian incursion" into Ukraine had occurred overnight in a "clear demonstration of continued Russian involvement in the destabilization of eastern Ukraine".
Niinisto was due to travel to Kiev directly from Sochi to meet Ukrainian President Petro Poroshenko on Saturday, his office said in a statement.
Putin said he was "seriously concerned" by the humanitarian situation in east Ukraine and would do his utmost to help end the military conflict there and establish dialogue between Kiev and the rebels.
REUTERS